Recent Distractions

Under The Dome
Stephen King

I've read most of Stephen King's book, and "Under the Dome" is clearly one of his best. It's the story of a small city suddenly cut off from the rest of the world by a transparent barrier, the "Dome." On the one hand it's one of these stories that show how many things we take for granted are quite fragile achievements of civilization, like water, electricity, or food supply. On the other hand, King masterly tells how the small-town leaders abuse their power and manipulate the town folks, while ordinary people find their inner hero. Of course the book also has a significant yuck-factor, King-style. The end leaves the scientist somewhat unsatisfied as to explanation, but then King isn't known as a sci-fi author.

Saturday
Ian McEwan

One long Saturday in the life of a neurosurgeon. It's an extremely well-told story with very carefully worked out and authentic characters. While there isn't actually much plot in this book, the reader gets to share the mind of the main character, his thoughts about current events, terrorism, the war in Iraq as well as aging and happiness in his own life. I found the book in parts quite annoying because of side-long detailed explanations about every move in a squash match or how to cook a bouillabaisse for dinner, but if you occasionally like to see the world through somebody else's eyes, this book is for you.

Solar
Ian McEwan

The main character of this novel is Michael Beard, a Nobelprize winner, now in his late 50s, with a long history of marriages and affairs. He doesn't see how he can make further contributions to physics, so he sets out getting famous in the flourishing business of clean energy and climate change. The story is a mixture of his private life with his attempt to leave a mark in history by not-so noble means The physics is sufficiently plausible, the author has clearly done his homework, and I found the story highly amusing and entertaining. As with "Saturday," by reading this book you'll get to see the world through somebody else's eyes. Very recommendable.

Duma Key
Stephen King

The main character of this book is Edgar who, after a work-accident that leaves him one-armed, loses also his wife and moves to Florida for a new start. There, he finds he has acquired a new talent, painting. And not only does he suddenly come to fame by his new talent, his paintings also have an eerie influence on his and other people's lives and bring him in contact with scary powers that awake from a long sleep. Together with newfound friends, Edgar sets out to battle these powers and put them back to sleep. It's a well-written story and an easy read, though there are repeated remarks about some good power watching over our heroes, so they "just know" what to do, which is never explained. The reader is left to wonder what this is all about, definitely not a feature I've encountered in earlier Stephen King novels.

Lisey's Story
Stephen King

King tell's the story of Lisey, the wife of a recently deceased famous who had, one could say, access to a parallel world. King being King, besides the writer's inspiration there's monsters and dangers lurking in that world. The story of that other world is woven together very nicely with Scott's family history and his marriage. The story is told after Scott's death, when Lisey has to deal with a mentally distorted person who is threatening her. However, the plot takes several hundred pages to actually start, and then lots of it doesn't make very much sense. Lisey is constantly following some intuitions for doing this or that which are never explained (similar to "Duma Key"), but she "just knows" it's the right thing to do. It's very unsatisfactory.

Nonsense people once believed in

I have a list with notes for blogposts, and one topic that's been on it for a while is believes people once firmly held that during the history of science turned out to be utterly wrong.

Some examples that came to my mind were the "élan vital" (the belief that life is some sort of substance), the theory of the four humors (one consequence of which was the wide spread use of bloodletting as medical treatment for all sorts of purposes), the static universe, and the non-acceptance of continental drift. On the more absurd side of things is the belief that semen is produced in the brain (because the brain was considered the seat of the soul), and that women who are nursing turn menstruation blood into breast milk. From my recent read of Annie Paul's book "Origins" I further learned that until only some decades ago it was widely believed that pretty much any sort of toxins are blocked by the placenta and do not reach the unborn child. It was indeed recommended that pregnant women drink alcohol, and smoking was not of concern. This dramatically wrong belief was also the reason why thalidomide was handed out without much concerns to pregnant women, with the know well-known disastrous consequences, and why the fetal alcohol syndrome is a fairly recent diagnosis.

I was collecting more examples, not very actively I have to admit, but I found yesterday that somebody saved me the work! Richard Thaler, director of the Center for Decision Research at the University of Chicago Graduate School of Business, is working on a book about the topic, and he's asked the Edge-club for input:

"The flat earth and geocentric world are examples of wrong scientific beliefs that were held for long periods. Can you name your favorite example and for extra credit why it was believed to be true?"

You find the replies on this website, which include most of my examples and a few more. One reply that I found very interesting is that by Frank Tipler:

"The false belief that stomach ulcers were caused by stress rather than bacteria. I have some information on this subject that has never been published anywhere. There is a modern Galileo in this story, a scientist convicted of a felony in criminal court in the 1960's because he thought that bacteria caused ulcers."

I hadn't known about the "modern Galileo," is anybody aware of the details? Eric Weinstein adds the tau-theta puzzle, and Rupert Sheldrake suggests "With the advent of quantum theory, indeterminacy rendered the belief in determinism untenable," though I would argue that this issue isn't settled, and maybe never will be settled.

Do you know more examples?

Interna

I’m stuck in the hospital again, thus my silence. The brief version is that my doc got nervous I might be in for preterm delivery. Now I’m getting medication that’s supposed to mature the babies lungs, just in case. Unfortunately these meds can have the side-effect of triggering labor, so to avoid that I get more medication (called tocolytics) to prevent the contractions. That medication then doesn’t only affect the muscles it should, but most importantly also the heart muscles, ie more side-effects, these of the very unpleasant sort. And then there’s more medication against the side-effects of that medication. The result is that I feel like shit, can’t go farther than up and down the corridor since I’m tied to an IV-drip, and my butt hurts from the injections. But otherwise we’re all fine. Below is a recent bump-photo from a surprisingly warm and sunny November weekend.



And if you think I was actually sleeping, just right of the photo, there's a table (you can see one edge) with a pile of papers on it...

This and That

• We discussed several times on this blog the question how plausible metrics for scientific success are, see for example my posts Science Metrics and Against Measure. This week, the NYT reports an amusing fact from the recent Times Higher Education university ranking in the article Questionable Science Behind Academic Rankings: Alexandria University in Egypt made it on the list on rank 147 (together with Uppsala) as the only Arab university. Just that, upon closer inspection, this success goes back to the enormous productivity of one researcher... and that is no other than Mohamed El Naschie. If you recall, two years ago we mentioned El Naschie's amazing publication record of more than 300 papers within a few years, published in a journal of which he also was editor-in-chief. He retired from his position a few weeks later. The NYT reports:
  

  “But the news that Alexandria University in Egypt had placed 147th on the list — just below the University of Birmingham and ahead of such academic powerhouses as Delft University of Technology in the Netherlands (151st) or Georgetown in the United States (164th) — was cause for both celebration and puzzlement. Alexandria’s Web site was quick to boast of its newfound status as the only Arab university among the top 200...
  
  Like most university rankings, the list is made up of several different indicators, which are given weighted scores and combined to produce a final number or ranking...
  
  Phil Baty, deputy editor of Times Higher Education, acknowledged that Alexandria’s surprising prominence was actually due to “the high output from one scholar in one journal” — soon identified on various blogs as Mohamed El Naschie, an Egyptian academic who published over 320 of his own articles in a scientific journal of which he was also the editor. In November 2009, Dr. El Naschie sued the British journal Nature for libel over an article alleging his “apparent misuse of editorial privileges.” The case is still in court.”


El Naschie commented the following on the university ranking:


“I do not believe at all in this ranking business and do not consider it anyway indicatory of any merit of the corresponding university.”



• Somehow scary:
  

  “In this edition, we have added, for the first time, annotated references in the text to provide the beginning of an evidence based approach to clinical methods.”

  
  From the preface of “Clinical Examination,” by Nicholas J Talley & Simon O'Connor, 4th Edition, 2001.


• The results from our recent poll: Is the scientific process one of discovery or invention? A total of 167 people took the poll. To my surprise, most them shared my opinion. The replies were: Both - 52.1%, Discovery - 33.7%, Invention -10.4%, Neither - 1.8%, Don't know - 1.8%.


• Chad Orzel discusses the statistic on the initial employment of new PhDs in physics from 1979 to 2008 in his post Physics Job Market: Same As It Ever Was. Slightly more than 50% of new PhDs presently go on to make a postdoc...
  
  You may find yourself living in a shotgun shack... and you may find yourself in another part of the world... You may ask yourself, "Well, how did I get here?"... Same as it ever was... Same as it ever was... (Talking Heads, Once in a Lifetime).


• And if you think that statistic doesn't look so bad, you may want to watch this:
  
  
  [Via Dynamics of Cats]
  
  You may ask yourself... How do I work this?
  

Religion: A temporary phase in mankind’s history?

I don’t often write on science and religion. That’s because it seems to me that everything that can be said was said about a million times already. But much of what I read recently tries to argue for or against the compatibility of religion and scientific research. The outcome is either some justification for denial of scientific facts or what’s become known as the “god of the gaps:” religion confined to these areas where scientific explanations are still lacking; an inevitably shrinking range of operation for god. But I believe that’s the wrong way to think about it.

Religion and science are not two different approaches to explain the world that need to be made compatible, possibly by discarding one entirely. Instead, religion (as well as other superstitious believes) is a historical pre-phase to scientific thinking. It’s a primitive exercise in story-telling and sense-making, that has proven to be of advantage for its practitioners. Religions are part of our historical legacy, but the wide spread of religion we currently witness is a temporary phase. Both are not compatible in the same sense that an MP3 player isn’t compatible with living in the Stone Age. But then, people in the Stone Age were happy even without MP3 players.

As an atheist, my interest in religion stems from them having a major influence on our history and their lasting effect in shaping our societies. It is an interesting question: Why is it that so many people, all around the globe, believe in some god when that god and its tales are in outright conflict with scientific evidence or, in the better case, without evidence whatsoever?

In an earlier post, I reported on results of a study looking for the neurological origin of religion. There have been a lot of studies in that direction during the last decade. Almost all of them however do not so much look for the origins of religiosity as more for the origins of supernatural thinking, or call it jumping to conclusions. The human brain looks for explanations, tries to find patterns, and to construct theories. These are skills that have proven very useful to our survival. Inventing gods arguably serves as some sort of explanation. Yet, superstition generally serves that purpose too, and at the end of the road, if you carefully follow up on the explanations, if you construct correct theories, where you inevitably arrive is: science! And over the course of history, that’s the path we’ve taken: Starting from gods and superstition towards science by continuing to ask and to look for better and more useful explanations.

Thus, one could equally well say our looking for patterns and aiming to construct explanations is not only the origin of religion, but the origin of scientific thinking and drawing upon such neurological basis to claim religion is hard-wired just confirms what we see in the world around us but doesn’t explain it. On that level, the difference between religion or superstition and science is simply how carefully you investigate the data and how much you learn about how to construct consistent theories of reality, ie the question is at which level of explanation do you stop searching. Tests for activity in certain brain regions look for activity on the very-short to short timescale. But that’s not all what constitutes human cognition. In contrast, compared to other species humans are particularly good in careful deliberation, reflection and advance planning. That’s the basis of our success. Not so surprisingly then, most, if not all, religious people sooner or later have doubts in the reality of what they believe in. This doubt has to be constantly silenced to be a good believer, and many people manage indeed to lull themselves into a state of constantly belying their own intelligence. But the existence of these doubts tells us that indeed religion is not the natural endstate of the search for explanation. The human mind wants to question and solve the puzzles. It wants to understand, not to be shut up. It wants to know more.

So, compared to science religions don’t make particularly convincing or useful explanations for anything and knowing what we know today, belief is only possible with working against ones’ own intelligence. We are then left to wonder still, why do so many people believe?

In a recent opinion piece on the NYT blog, Tim Crane (who declares himself an atheist) wrote, in essence, that people chose to believe because it’s easier:

“[S]cientific explanation is a very specific and technical kind of knowledge. It requires patience, pedantry, a narrowing of focus and (in the case of the most profound scientific theories) considerable mathematical knowledge and ability...

Religious belief is a very different kind of thing. It is not restricted only to those with a certain education or knowledge, it does not require years of training, it is not specialized and it is not technical. (I’m talking here about the content of what people who regularly attend church, mosque or synagogue take themselves to be thinking; I’m not talking about how theologians interpret this content.)...

I would guess that very few people in the world are actually interested in the details of contemporary scientific theories... [M]ost people aren’t deeply interested in science, even when they have the opportunity and the basic intellectual capacity to learn about it.”

I don’t find this explanation plausible. True, if one wants to understand the details of modern science it requires time and effort. But that’s true for everything, including religion, as Crane points out himself. Understanding the Bible (to the extent possible) also requires patience and a narrowing of focus. It would already make a difference if more people would at least understand contemporary science on the level they understand their weekly sermon. No, the actual reason why people have more knowledge about their religion than, say, modern cosmology, is that they go to church every Sunday instead of going to a physics lecture. Their mindset is a consequence, rather than the origin of what they spend time on. Just think about how amazingly quickly seriously ill patients learn details about their disease, up to the level where they know more about recent research than their doctors. Suddenly they are deeply interested indeed, it’s just a matter of motivation.

With Crane’s explanation not being convincing, let us ask again: why do so many people believe? I think it’s because religious belief has both psychological as well as social advantages, and that serves as a motivation science is often lacking. Let us start with the psychological advantage. Existential psychotherapy is a particularly simple (and overly simple) model of the human mind. It posits that we all have four so-called “existential fears” – the fear of death, of loneliness, of meaninglessness and the fear of freedom. (The latter refers to the fear of responsibility one has for one’s own decisions.) Psychological problems occur if one or several of these fears take overhand and stifle personal development. Religions neatly address all of these fears. The social advantage comes from being a member of a global community with shared traditions that in many cases are very well organized, providing counseling and support in difficult phases of one’s life. The believer belongs, and he knows where he belongs.

Thus, the practitioner of a widely spread religion has indeed benefits from his belief. The benefits are less pronounced for superstition for which there is no such social cohesion and does less to address existential fears, thus explaining why the neurological origin might be the same but religions are more successful.

The question is now what has science to offer?

On the psychological and social level, science has no such offers to make – at least not yet, and not obviously so. But I think these offers will come, and they will become more and more widely accepted.

On the social level, I don’t think it is farfetched that one day people do indeed go to a public lecture on science every Sunday instead of going to church (must be one of my optimistic days). And the sense of community, that some of you might have found already on the Internet, comes automatically with the spread of shared knowledge, and time and places where you know you will meet like-minded people to discuss what's on your mind. Today, if you are actively working in science, you’ll find your community easily at the next university, all over the globe. Departments of physics look the same everywhere. If you’ve been in the field for some while, you’ll feel at home in either one. Same posters on the wall, same books in the shelves, same topics over lunch. I guess it is similar in most other fields: Science is a global enterprise.

On the psychological level, let us first mention again that science has the advantage of allowing –indeed welcoming – skepticism and doubt. The disadvantage is that one has to accept uncertainty as necessary ingredient. Science does not address the four existential fears as directly as religion does, but it does to some extent and that’s becoming more and more noticeable. There are for example numerous research programs trying to understand, explain, and modify human mortality. Of course these are on very different levels of scientific rigor and plausibility (ranking from freezing in one’s brain, over uploading oneself to a computer, to improving the body’s DNA repair mechanism). And of course they are not as complete comfort as believing in an immortal soul that goes to heaven or is reborn, but they offer a ground to grapple with the process of one’s own aging and death. The fears of loneliness, meaninglessness, freedom: There is lots of scientific research which addresses one or the other, on social, neurological, psychological, or philosophical grounds. That again is becoming more and more noticeable. Just have a look at the abundance of self-help books (e.g. on the topic of happiness). Yes, most of them are based on pseudo-science rather than sound science, but at least it’s a start. The point is not the quality of the science, the point is these approaches are non-religious. It’s a begin of a change of which I’m convinced we’ll see more.

And finally, of course a major role is played by the ancient questions: Where do we come from? and What are we made of? Theoretical physics is on the most fundamental level of our search for explanations. This is why the questions asked in this field seem quite detached from life and understanding current research – and its relevance – takes time and effort indeed. But it is this research we need to truly understande our place in the universe.

Americans prefer Swedish wealth distribution

I was a little bit depressed about the recent US midterm election. Not so much because of the outcome. I wasn't too convinced of Obama when he was elected. The way his campaign went, I was afraid he'd turn out to be a populist and change his course every time some interest group's wishes made it into the headlines. But I severely underestimated the man. In contrast to most of the commentators on the outcome of the midterm election, he is evidently well aware that halfway through his term he's in a lose-lose situation anyway. Either he keeps his course and is being criticized for not being a miracle healer, or he'd listen to the masses and claim he changed his mind and be criticized for that. Whether one thinks his political agenda is promising or not, in that situation at least he's aiming at doing the right thing in the course of history, rather than doing the right thing to be re-elected. In January, Obama said:

"I'd rather be a really good one-term president than a mediocre two-term president."

A rare case of a politician with a backbone. Given that, I can't say I was surprised by the election outcome. No, what depressed me was the lacking substance of arguments. The American nation strikes me as similar to a group of overweight people who at their first weight watchers meeting chants "Yes, we can" and cheer upon change. But when change is staring back from the dinner plate, and change on the scale leaves waiting, they realize change doesn't come easy. And the vast majority of them still doesn't know the difference between social democracy and socialism. Clearly, the world would be a better place if everybody would read my blog ;-)

Anyway, to some extend I don't care very much how the Americans organize their society. I think they're not fully using their potential, and find that a shame, but after all it's their decision what they put on their plates and shovel down their throats while I, well, I live in Sweden. And that brings me to one of the most amusing studies I've come across lately:

Building a Better America – One Wealth Quintile at a Time
By Michael I. Norton and Dan Ariely, PDF here

Michael Norton, from Harvard Business School, and his colleague Dan Ariely, from Duke University, asked a random sample of US citizens what wealth distribution they think is ideal. In 2005, they surveyed 5,522 people. Asked for their voting pattern in the 2004 election, the sample reproduced well the actual voting result. The survey respondents were given a definition for wealth so there was no ambiguity. Then they were shown three pie charts. Each slice of the pie represents 20% of the population, from the poorest to the wealthiest. The size of the slice is the wealth owned by this group. One pie showed a perfectly equal distribution. The other two pies were unlabeled but showed the distribution of the USA and that of Sweden.

The result: 47% of Americans preferred the Swedish wealth distribution, followed by 43% for the equal distribution, while only 10% found ideal the actual distribution. Just focusing on the Swedish vs the US distribution, 92% of Americans prefer the Swedish one over their own.

[Source: Fig 1 of this paper]
It turns out that these preferences depend only very little on demographic factors like gender or whether they voted for Bush or Kerry in 2004. Considered how convinced Americans tend to be about their own greatness, this result seems somewhat puzzling. However, keep in mind that these pie charts were unlabeled in the questionnaire. The replies makes sense if you come to the next question. In that, survey respondents were asked first to guess the wealth distribution in the USA, and then chose what distribution they would find ideal. It turns out that most Americans severely underestimate the rich-poor gap in their own country, and in addition would prefer a distribution that is even more equal than their erroneous estimate. This is shown in the figure below.

[Source: Fig 3 of this paper]
Again, note how little both the estimate as well as the ideal depends on demographic factors.

This result fits quite well with previous studies which had shown that Americans overestimate the social mobility in their own country. They're still dreaming the American dream, despite its evident conflict with reality.

After I stopped laughing I started wondering what this result really means. The survey respondents are very clearly considering the present wealth distribution as not ideal. However, the wealth distribution is a fairly abstract observable. Would you have been able to accurately estimate it? My own estimate would have been considerably closer to the actual one than the average guess, but that's only because I happen to have seen the relevant numbers before.

Norton and Ariely had a good reason to ask these questions: The philosopher John Rawls proposed that justice should be identified by taking a position behind a "veil of ignorance." For that, you're supposed to imagine that you decide on a particular question - for example the distribution of wealth - and only after you've decided you'll be randomly assigned a position within that society you've just created. I've never been really convinced by that approach. It's much too heady, or call it utopian. As a matter of fact, people don't live behind a veil of ignorance and their own social status does influence their decisions. Also, it isn't only the ideal (size 4!) that's relevant but also the way to get there (diet). In fact, the way is typically the question that's more immediate and thus more prominent on people's mind.

If one just asks people what they think is ideal, you're probing their ideas about what they believe the wealth distribution means, not necessarily what they actually want. To get to the relevant point, one would have to ask for factors that actually affect their life, or are such that they have some basis to judge on. Social mobility for example, the possibilities that are open for them and their children, is a relevant factor, and it is of course related to the wealth distribution. Or, instead of asking for the distribution of wealth, maybe better ask if they think somebody's work is really worth a 1000 times more than somebody else's. Another factor, and the one that bothers me most, is that wealth means power and it means influence. How much influence on your life do you want a small group of people to have? And at which point does this run into conflict with democratic decision making?

Bottomline: This is an interesting study. It explains a lot of things about the US American attitude towards their country's income distribution and the sometimes puzzling disconnect between their wish for change on the one hand and on the other hand their unwillingness to really take the necessary steps: they believe the steps are smaller than they in fact are. However, it's not a result that should have any relevance for policy decisions because the question asked is impractical. One doesn't chose a wealth distribution first and then gets randomly assigned a place in that society. It's not how things work in real life, and it's just replacing one dream with another one. There's always the risk the dream might later turn out to be a nightmare.

Aside: Dan Ariely, one of the authors of the study, writes a blog. He commented on his own paper here.

Learning: school versus university

Two days ago, a young man about to finish high school told me he couldn’t decide whether to study mathematics, informatics or physics. If I would have any advice? Though physics is interesting at school, he doesn’t really like it because there is so much to learn, he said. Math on the other hand he likes better because once understood, one just has to do it.

My first reaction was if you dislike learning, a university isn’t the right place for you no matter what field you chose. Then I thought he might be disliking not learning in general, but a particular sort of learning. It might be useful to distinguish the following four types of learning:

1. Physical learning
   Is the training of motion sequences through practice and exercise. Plays a major role for sports, playing an instrument, driving, and so on. It’s aiming for the goal, doing your scales practice, filling cuvettes till you manage without spilling, etc.


2. Learning by doing
   Is learning from cause and effect, trial and error. Omnipresent theme of children’s toys and school education. Many science museums too work with push here - look there. In contrast to physical learning though, the emphasis is not on learning a particular motion but understanding a relation.


3. Knowledge gathering
   Is the classical learning of facts and data. Avogadro’s number is about 6 x 10²³. The capital of turkey is Ankara. The milky-way is about 100,000 light-years side to side. The can-opener was invented 48 years after the can. Etc.


4. Conceptual understanding
   Is the learning of explanations and relations, theories and concepts. What is chaos? How does the stock market work? What makes airplanes fly? Why doesn’t the moon fall down on Earth?

Learning at school as well as at the university is typically a combination of these 4 types of learning. But the composition depends on the field, and it may substantially change from school to university. Languages for example are generally heavy in knowledge gathering. You just have to memorize that vocabulary, no way around it. And you can’t lead any argument in history without the names and dates. Biology, chemistry, physics and mathematics necessitate type 3 learning in declining order. Lab work is the contribution from 2.

At school, you will generally do well just by learning the facts and it is, at least in my experience, also often where the emphasis of the educational system is (except for classes like sports and music which rely on type 1 learning). Especially in mathematics however, it is possible already in school to replace type 3 learning with type 4 learning: You can either memorize a table with functions and their derivative and integrals, or you understand what a derivative and an integral is. You learn the steps you have to do to calculate the intersection of two planes in a 3-dimensional space. Or you understand what the equations mean. Pupils who fly through math are typically those who understand the concepts, rather than learning a scheme for computation.

When you finish school and start studying math or physics, the relevance of memorizing facts drops dramatically. Who cares if you know Avogadro’s number - you can go look it up if you need it. Sure, it’s handy to know the distance from Earth to Sun, but it’s not going to impress your prof. In mathematics, the break with school practice is particularly dramatic. What you’ve done at school doesn’t prepare you for studying mathematics at all, except that some symbols might look vaguely familiar. To quote my younger self:

[W]hat's called mathematics in school has little to do with mathematics. It should more aptly be called calculation. Don't get me wrong, it is essential knowledge to be able to multiply fractions and calculate percentage rates, but it has about as much to do with mathematics as spreading your arms has with being a pilot. Problem is, that's about all most people ever get to know of mathematics. The actual heart of math however is not number crunching or solving quadratic equations, it's the abstraction, the development of an entirely self-referential, logically consistent language, detached from the burden of reality.

Both Stefan and I can recall from our first semesters those students who tried to continue type 3 learning that had worked so well at school. You can indeed just learn by heart what your textbook says what the variational principle is, and reproduce the relevant sentences when asked. You can memorize every example discussed in class, and learn technical terms by writing down definitions on a stack of index cards. This might get you through the first few semesters, but it’s not going to work in the long run. Both Stefan and I have seen dropping out the fellow students who proceeded this way, one after the other.

To come back to the young man’s question. If what you dislike in physics at school is the emphasis on type 3 learning, chances are you’ll do just fine at the university. There’s still the lab exercises where you have to stare at glowing wires for several hours or find anything else on the oscilloscope besides the 50 Hz curve, but if I managed that you can do it too.

I started studying mathematics and only changed to physics after my bachelor’s degree. That was possible because I had taken all the necessary classes and the department of mathematics had a respective agreement with the department of physics. It didn’t cause me any problems, and pretty much all of the additional math came in handy at some later point. I don’t know much about the requirements for informatics, but what I know from friends is that the first semesters are very heavy in math too. So in case of doubt, I’d recommend to start with math because the change to either physics or informatics will be easier than if you do it in any other order. However, since the time I was in my first semesters many regulations have changed to accommodate the European master’s program. I don’t know if, or under which conditions, it is still possible to change field after the first semesters.

In summary: Don’t expect that physics or math at the university is a continuation of what you’ve done at school, neither for what success or boredom is concerned. Best is to primarily follow your interests because you will need perseverance and motivation.

Book Review: "Origins" by Annie Murphy Paul

Origins
How the Nine Months Before Birth Shape the Rest of Our Lives
By Annie Murphy Paul
Free Press (September 28, 2010)

I thought the acronym FOAD stands for fuck off and die, but Annie Paul taught me it stands for "Fetal Origins of Adult Disease." Maybe I wasn't the only one with that association, because from her book "Origins, How the Nine Month Before Birth Shape the Rest of Our Lives" I also learned that this research field was later renamed into DOHaD - "Developmental Origins of Health and Disease." And that's what her book is about: The increasing amount of scientific evidence that besides our genetic inheritance and individual experience, who we are and what we will be is influenced by a third, and long neglected, factor - the nine months spent inside our mother's womb.

As the renaming of this flourishing research area indicates, these are interesting studies not only to understand the origins of diseases, but also as guides to the health of coming generations. Unlike our genetic information, the conditions in utero are to some extend accessible for prevention and intervention. It has long been known for example that the same genetic information (genotype) might come in different appearances (phenotype), but exactly how this mechanism works and how the phenotype is affected in particular during gestation has only recently become accessible to scientific investigation.

Annie Paul is a science journalist, and her book is a survey of recent and not-so recent studies on DOHaD, together with historical anecdotes and reports of interviews with scientists, all woven together with the story of her own pregnancy. The book's chapters are (guess) month one to nine, and the reference list is extensive. It is a well-written, classical and flawless piece of a good science journalism. It also comes with the typical weaknesses of the genre. While Paul has thoroughly scanned the literature, she reports rather than explains, and if she has an own opinion on a particular controversial issue, she does not offer it. Since in addition a book on such a popular level cannot explain in much detail the studies it reports on, the reader who doesn't go and check the literature himself has little chances to form an informed opinion. While Annie Paul cleans up with a few decade old myths (for example the advise that showering with baking soda increases the chances of conceiving a boy) most of her book is a collection of topics and studies presently under discussion, and also an outlook on studies planned and consequences of what we have learned or may learn.

She covers the influence of traumatic experiences and stress on the developing fetus, environmental toxins, drugs and medication, and preexisting conditions of the mother (such as overweight or diabetes). The reader learns that there are studies that claim to have shown eating a bowl of cereal in the morning increases a mothers' chance of having a boy - and others that claim the result is nonsense, that a mother's experience of high stress or periods of hunger affects more strongly the survival chances of male than female fetuses, and that daily chocolate consumption of a pregnant woman results in happier babies. Paul also briefly touches on economical factors, citing studies that have shown people born in periods of hunger or wide-spread disease do on the average have a lesser income as adults than those who were born before or conceived after the tough times.

Annie Paul does mostly just document the research, but a few paragraphs here and there she takes on the question what the impact of this research may be on our societies in the future and what the benefit of this area of science may be. She hopes that babies born in difficult social situations - often correlated with malnutrition, drug abuse, stress or trauma - will have chances of doing better than their parents if special care is taken of pregnant woman, or children at risk for problems can be identified in advance and offered targeted help. She also hopes that in cases of natural disasters or war, mothers-to-be will receive psychological support to prevent their babies from being affected.

This all sounds very sensible, but on several instances Paul comes close to arguing for this additional care by an improved economic output: Healthy and happy children grow up to be more productive adults, so our societies should have an interest in this investment. I have encountered similar arguments repeatedly when it comes to health care, and I am wary of the implications. It is a quite slippery slope. If you step on it, you easily slide down to where you'll find that investments that will not pay off should not be made. It is however very likely that understanding the origins of adult's diseases and problems will in some cases lead to a better understanding, but a treatment may not pay off in economic terms. To me, it is more a matter of empathy and solidarity, than one of productivity, to offer such support.

Taken together, Annie Paul's book has provided me with a bulk of interesting and entertaining study results, yet with little insight as to their scientific credibility. It has given me an excuse to munch down Stefan's chocolate, reminded me of the weakness of the male part of our species, and caused me a bad consciousness for not clearing my household of plastics containing Bisphenol A, whether or not scientists will eventually find them reason for concern. Paul's book is an easy read, yet I would have appreciated a somewhat deeper coverage of the underlying science. I'd give this book 3 out of 5 stars if I'd have stars to give - in other words, it's not a must-read, you can wait for the paperback version.

Interna

For those of you who've been asking how my pregnancy is going, here's a brief update.

Unfortunately, I'm having some complications that prompted the doctors to put me on medication and bed rest already several weeks ago. I've been on sick leave since, trying to stay horizontally as much as possible, having weekly check-ups. After last week's exam the doctor recommended if I plan on taking any flights before delivery, I should do so rather sooner than later.

So I packed my bag, rebooked my flight - and now I'm back in Germany. The prospect of staying here for almost half a year is admittedly odd. I haven't lived in Germany for almost 7 years now. When I moved to Arizona for my first postdoc I never meant to stay away more than a year. You'd have told me then I'd only come back after a detour through California, Canada, and Sweden, in late 2010, 7 months pregnant with twins, to move in with a guy I've been married to for more than 4 years yet have never shared an apartment with, I'd have declared you nuts.

Funny, the way life goes, eh?

In any case, moving in with Stefan some weeks earlier than planned means I've stepped right into his moving chaos. We're sitting on boxes, waiting for phone and internet, and have no kitchen appliances. Also, we're facing difficult decisions. For example, Stefan is left-handed but I am right-handed. So which side of the toilet do we put the paper?

The babies meanwhile are doing fine, growing properly and kicking stronger every day. My belly's size is presently that of a nine month single pregnancy, yet scarily enough has to grow 10 more weeks.

News to me is that Halloween has become a seasonal event in Germany. When I was a kid, that tradition was pretty much unknown here. Now, people have carved pumpkins on their doorsteps, stock up on candy and welcome another opportunity to go out and get drunk. No, I didn't carve a pumpkin. I feel like one myself, that's enough seasonal event for me.

Within the last decade or so, Germany has also seen a boom of new shopping malls outside the city centers. On the weekend, Stefan and I went to Starbucks in one of these malls in the area. Half of the guests seemed to be Americans, probably because the US Army has troops in nearby Mannheim, and really, where can you go on a weekend other than Starbucks? The whole place was eerily non-national, and crowded in addition, so we ordered our coffees to go. Then somebody left and I managed to occupy a table. Sitting there with the paper cups quickly got us a reprimand from the barista for producing unnecessary garbage. Suddenly the air smelled German again.

This and That

With the weekend approaching, here's some distractions to kill your remaining working hours till 5pm:

• A very nice applet that zooms you through the scales of the universe, all the way down to the Planck length.


• An interesting recollection by Robert Weisbrot of Edward Witten's way to physics:
  
  "I am reminded of a friend from the early 1970s, Edward Witten. I liked Ed, but felt sorry for him, too, because, for all his potential, he lacked focus. He had been a history major in college, and a linguistics minor. On graduating, though, he concluded that, as rewarding as these fields had been, he was not really cut out to make a living at them. He decided that what he was really meant to do was study economics. And so, he applied to graduate school, and was accepted at the University of Wisconsin. And, after only a semester, he dropped out of the program. Not for him. So, history was out; linguistics, out; economics, out. What to do? This was a time of widespread political activism, and Ed became an aide to Senator George McGovern, then running for the presidency on an anti-war platform. He also wrote articles for political journals like the Nation and the New Republic. After some months, Ed realized that politics was not for him, because, in his words, it demanded qualities he did not have, foremost among them common sense. All right, then: history, linguistics, economics, politics, were all out as career choices. What to do? Ed suddenly realized that he was really suited to study mathematics. So he applied to graduate school, and was accepted at Princeton. I met him midway through his first year there--just after he had dropped out of the mathematics department. He realized, he said, that what he was really meant to do was study physics; he applied to the physics department, and was accepted.
  
  I was happy for him. But I lamented all the false starts he had made, and how his career opportunities appeared to be passing him by. Many years later, in 1987, I was reading the New York Times magazine and saw a full-page picture akin to a mug shot, of a thin man with a large head staring out of thick glasses. It was Ed Witten! I was stunned. What was he doing in the Times magazine? Well, he was being profiled as the Einstein of his age, a pioneer of a revolution in physics called "String Theory." Colleagues at Harvard and Princeton, who marvelled at his use of bizarre mathematics to solve physics problems, claimed that his ideas, popularly called a "theory of everything," might at last explain the origins and nature of the cosmos. Ed said modestly of his theories that it was really much easier to solve problems when you analyzed them in at least ten dimensions. Perhaps. Much clearer to me was an observation Ed made that appeared near the end of this article: every one of us has talent; the great challenge in life is finding an outlet to express it. I thought, he has truly earned the right to say that. And I realized that, for all my earlier concerns that he had squandered his time, in fact his entire career path--the ventures in history, linguistics, economics, politics, math, as well as physics--had been rewarding: a time of hard work, self-discovery, and new insight into his potential based on growing experience."
  
  [Via Michael Nielsen, via Hacker News. Read the full speech here.]


• You might already have read it on Nature News: Astronomers have found the to date most massive neutron star with about 2 solar masses. When I read this, a bell was ringing faintly in the dusty back of my head. Meanwhile I've figured out what was ringing: Smolin's Cosmological Natural Selection predicts an upper mass limit for neutron stars of 1.6 solar masses. (See hep-th/0612185, section 3.2).


• Some months ago I was sent a link to an April fools day paper, funny-haha, physicists style. That paper has now resurfaced on my desk: Schrödinger's Cat is not Alone. It's a humorous take on the interpretation of quantum mechanics and cat dynamics. Not the sort of humor that deepens my laugh wrinkles, but I thought some of you might find it amusing.


• Here's something that did give me a good laugh. Real life absurdity:
  Nurses find the weirdest stuff. [Via Bora].

I wish you all a nice weekend!

Short-term thinking

Science, especially fundamental research, used to be a pastime of the rich. Within the last century its potential for innovation has been discovered. Today, fundamental research is widely recognized as an investment of our societies into the future. While this societal support and appreciation has opened the stage for everybody to participate, it came with a side-effect. Research is being more and more confined and run by the same rules that have been efficient for the producing and service-providing parts of our economies, the standards that are being used by corporations and companies, the framework that policy makers are used to think in. While this is not a complete disaster - after all science does still work remarkably well - the problem is that it is not an approach which works for all sorts of research.

I have discussed at this blog many times the differences and similarities between the "Marketplace of Ideas" and the free marketplace of products. The most relevant difference is the property the system should optimize. For our economies it is profit and - if you believe the standard theory - this results ideally in a most efficient use of resources. One can debate how well the details work, but by and large it has indeed worked remarkably well. In the academic system however, the property to optimize is "good research" - a vague notion with subjective value. Before nature's judgement on a research proposal is available, what does or doesn't constitute good research is fluid and determined by the scientific community, which is also the first consumer of that research. Problems occur when one tries to impose fixed criteria for the quality of research, some measure of success. It sets incentives that can only deviate the process of scientific discovery (or invention?) from the original goal.

That is, as I see it, the main problem: setting wrong incentives. Here, I want to focus on a particular example, that of accountability and advance planning. In many areas of science, projects can be planned ahead and laid out in advance in details that will please funding agencies. But everybody who works in fundamental research knows that attempting to do the same in this area too is a complete farce. You don't know where your research will take you. You might have an idea of where to start, but then you'll have to see what you find. Forced to come up with a 3-year, 5 point plan, I've found that some researchers apply for grants after a project has already been finished, just not been published, and then spend the grant on what is actually their next project. Of course that turns the whole system ad absurdum, and few can afford that luxury of delaying publication.

The side-effect of such 3-year pre-planned grants is that researchers adapt to the requirements and think in 3-years pre-plannable projects. Speaking about setting incentives. The rest is good old natural selection. The same is true for 2 or 3 year postdoc positions, that just this month thousands of promising young researchers are applying for. If you sow short-term commitment, you reap short-term thinking. And that's disastrous for fundamental research, because the questions we really need answers to will remain untouched, except for those courageous few scientists who willingly risk their future.

Let us look at where the trends are going: The number of researchers in the USA holding faculty positions 7 years after obtaining their degree has dropped from 90% in ’73 to 60% in 2006 (NSF statistics, see figure below). The share of full-time faculty declined from 88% in the early 1970s to 72% in 2006. Meanwhile, postdocs and others in full-time nonfaculty positions constitute an increasing percentage of those doing research at academic institutions, having grown from 13% in 1973 to 27% in 2006.



The American Association of University Professors (AAUP) has compiled similar data showing the same trend, see the figure below depicting the share of tenured (black), tenure-track (grey), non-tenured (stripes) and part-time (dots) faculty for the years 1975, 1989, 1995 and 2007 [source] (click to enlarge).


In their summary of the situation, the AAUP speaks clear words "The past four decades have seen a failure of the social contract in faculty employment... Today the tenure system [in the USA] has all but collapsed... the majority of faculty work in subprofessional conditions, often without basic protections for academic freedom."

In their report, the AAUP is more concerned with the quality of teaching, but these numbers also mean that more and more research is done by people on temporary contracts, who at the time they start their job already have to think about applying for the next one. Been there, done that. And I am afraid, this shifting of weight towards short-term thinking will have disastrous consequences for the fundamental research that gets accomplished, if it doesn't already have them.

In the context of setting wrong incentives and short-term thinking another interesting piece of data is Pierre Azoulay et al's study

Incentives and Creativity: Evidence from the Academic Life Sciences
By Pierre Azoulay, Joshua S. Gra Zivin, Gustavo Manso
(PDF here)

In their paper, the authors compared the success of researchers in the life sciences funded under two different programs, the Howard Hughes Medical Institute (HHMI), which "tolerates early failure, rewards long-term success, and gives its appointees great freedom to experiment" and the National Institute of Health (NIH), with "short review cycles, pre-defined deliverables, and renewal policies unforgiving of failure." Of course the interpretation of the results depends on how appropriate you find the used measure for scientific success, the number of high-impact papers produced under the grant. Nevertheless, I find it tale-telling that, after a suitable adjustment of researcher's average qualification, the HHMI program funding 5 years with good chances of renewal produces a better high-impact output than the NIH 3 year grants.

And speaking of telling tales, let me quote for you from the introduction of Azoulay et al's paper which contains the following nice anecdote:

"In 1980, a scientist from the University of Utah, Mario Capecchi, applied for a grant at the National Institutes of Health (NIH). The application contained three projects. The NIH peer-reviewers liked the first two projects, which were building on Capecchi's past research effeorts, but they were unanimously negative in their appraisal of the third project, in which he proposed to develop gene targeting in mammalian cells. They deemed the probability that the newly introduced DNA would ever fi nd its matching sequence within the host genome vanishingly small, and the experiments not worthy of pursuit.

The NIH funded the grant despite this misgiving, but strongly recommended that Capecchi drop the third project. In his retelling of the story, the scientist writes that despite this unambiguous advice, he chose to put almost all his efforts into the third project: "It was a big gamble. Had I failed to obtain strong supporting data within the designated time frame, our NIH funding would have come to an abrupt end and we would not be talking about gene targeting today." Fortunately, within four years, Capecchi and his team obtained strong evidence for the feasibility of gene targeting in mammalian cells, and in 1984 the grant was renewed enthusiastically. Dispelling any doubt that he had misinterpreted the feedback from reviewers in 1980, the critique for the 1984 competitive renewal started, "We are glad that you didn't follow our advice."

The story does not stop there. In September 2007, Capecchi shared the Nobel prize for developing the techniques to make knockout mice with Oliver Smithies and Martin Evans. Such mice have allowed scientists to learn the roles of thousands of mammalian genes and provided laboratory models of human afflictions in which to test potential therapies."

If you're interested in the phenomenology of quantum gravity...

... you might want to check out my recent paper

Experimental Search for Quantum Gravity
arXiv:1010.3420v1 [gr-qc]

It's not very technical, so don't hesitate to have a look. It's basically a summary of interesting developments and hopefully explains why I like working in the area. If you're not from the field, you might stumble over one or the other expression, but I think you'll still get a pretty good impression what it's all about.

Science changes, for real

I recently read an interesting article by Jeffrey R. Young in the Chronical of Higher Education, titled Crowd Science Reaches New Heights. It tells the story of Alexander S. Szalay, professor of physics and astronomy at the Johns Hopkins University, who has played a major role in making astronomical data a public resource. The whole article is very readable, so if you have the time, check it out. Here, I just want to quote a snippet that documents vividly how much science has changed within the last decade:

"The astronomical community did not believe we would ever really make the data public," says Mr. Szalay. The typical practice in the mid-1990s was to guard data because it was so difficult to get telescope time, and scholars did not want to get scooped on an analysis of something they gathered.

One incident demonstrates the mood at the time. A young astronomer saw a data set in a published journal and wanted to reanalyze it, so he asked his colleague for the numbers. The scholar who published the paper refused, so the junior scholar took the published scatterplot, guessed the numbers, and published his own analysis. The original scholar was so upset that he called for the second journal to retract the young scholar's paper.

Mr. Szalay said that astronomers changed their minds once the first big data sets hit the Web, starting with some images from NASA, followed by the official release of the first Sloan survey results in 2000.

I was surprised by that anecdote, but then I only started working in physics in '97. I recall though converting one or the other figure into a table to be able to reuse the data - an extremely annoying procedure, even with the use of suitable software. However, these were figures from decade-old textbooks, the data of which I needed to check whether a code I had written would make a sufficiently good fit. And 5 years back or so, when I had a phase of sudden interest in neutrino physics, I noticed that while one finds plenty of papers on the results of Monte-Carlo simulations to fit neutrino experiments, the data used is not for all experiments listed. In one case, I ended up browsing a bulk of Japanese PhD thesis (luckily in English) till I found the tables in the appendix of one, and then I had to type them off. Not sure how much the situation in that area has changed since. But change is inevitably on its way...

test* the hypothes*

I recently came across a study in the sociology of science and have been wondering how to interpret the results:

Do Pressures to Publish Increase Scientists' Bias? An Empirical Support from US States Data
By Daniele Fanelli
PLoS ONE 5(4): e10271. 1

There are many previous studies showing that papers are more likely to get published and cited if they report "positive results." Fanelli now has found a correlation between the likeliness of reporting positive results and the total number of papers published in a sample of papers with a corresponding author in the USA, published in the years 2000 - 2007, across all disciplines. The papers were sampled by searching the Essential Science Indicator's database with the query "test* the hypothes*" and then the sample was separated into positive and negative results by individual examination (both by the author and by an assistant). The result was as follows:

In a random sample of 1316 papers that declared to have “tested a hypothesis” in all disciplines, outcomes could be significantly predicted by knowing the addresses of the corresponding authors: those based in US states where researchers publish more papers per capita were significantly more likely to report positive results, independently of their discipline, methodology and research expenditure... [T]hese results support the hypothesis that competitive academic environments increase not only the productivity of researchers, but also their bias against “negative” results.

When I read that, I was somewhat surprised about the conclusion. Sure, such a result would "support" the named hypothesis in the sense that it didn't contradict it. But it seems to me like jumping to conclusions. How many other hypothesis can you come up with that are also supported by the results? I'll admit that I hadn't even read the whole paper when I made up the following ones:

• Authors who publish negative results are sad and depressed people and generally less productive.


• A scientist who finds a negative result wants more evidence to convince himself his original hypothesis was wrong, thus the study takes longer and in toto less papers are published.


• Stefan suggested that the folks who published more papers are of the sort who hand out a dozen shallow hypothesis to their students to be tested, and are likely to be confirmed. (Stefan used the, unfortunately untranslatable, German expression "Dünnbrettbohrer," which means literally "thin board driller.")

After I had read the paper, it turns out Fanelli had something to say about Stefan's alternative hypothesis. Before I come to that however, I have to say that I have an issue with the word "positive result." Fanelli writes that he uses the term to "indicate all results that support the experimental hypothesis." That doesn't make a lot of sense to me, as one could simply negate the hypothesis and find a positive result. If it was that easy to circumvent a more difficult to publish, less likely to be cited, summary of ones research results, nobody would ever publish a result that's "negative" in that sense. I think that in most cases a positive result should be understood as one that confirms a hypothesis that "finds something" (say, an effect or a correlation) rather than one that "finds nothing" (we've generated/analyzed loads of data and found noise). I would agree that this isn't well-defined but I think in most cases there would be a broad agreement on what "find something" means, and a negation of the hypothesis wouldn't make the reader buy it as a "positive result." (Here is a counter-example). The problem is then of course that studies which "find nothing" are equally important as the ones that "find something," so the question whether there's a bias in which ones are published is important.

Sticking with his own interpretation, Fanelli considers that researchers who come to a positive result, and in that sense show themselves correct, are just the smarter ones, who are also more productive. He further assumes that the more productive ones are more likely to be found at elite institutions. With his own interpretation this alternative hypothesis doesn't make a lot of sense, because when the paper goes out, who knows what the original hypothesis was anyway? You don't need to be particularly smart to just reformulate it. That reformulation however doesn't make a non-effect into an effect, so let's better consider my interpretation of "positive result." Fanelli argues the explanation that people smart enough to do an experiment where something is to be found are also the ones who publish more papers generally doesn't explain the correlation for two reasons: First, since he assumes these people will be at elite institutions, there should be a correlation with R&D expenditure, which he didn't find. Second, because this explanation alone (without any bias) would mean that in states where 95% - 100% of published results were positive, the smart researchers hardly every misjudged in advance the outcome of an experiment and the experiment was always such that the result was statistically significant, even though other studies have shown that this is not generally the case.

To the alternative hypothesis that Stefan suggested, Fanelli writes:

A possibility that needs to be considered in all regression analyses is whether the cause-effect relationship could be reversed: could some states be more productive precisely because their researchers tend to do many cheap and non-explorative studies (i.e. many simple experiments that test relatively trivial hypotheses)? This appears unlikely, because it would contradict the observation that the most productive institutions are also the more prestigious, and therefore the ones where the most important research tends to be done.

Note that he is first speaking about "states" (which was what actually went into his study) and then later about "institutions." Is it the case indeed that the more productive states (that would be DC, AZ, MD, CA, IL) are also the ones where the most important research is done? It's not that I entirely disagree with this argument, but I don't think it's particularly convincing without clarifying what "most important research" means. Is it maybe research that is well cited? And didn't we learn earlier that positive results tend to get better cited? Seems a little circular, doesn't it?

In the end, I wasn't really convinced by Fanelli's argument that the correlation he finds is a result of systematic bias, though it does sound plausible, and he did verify his own hypothesis.

Let me then remark something about the sample he's used. While Fanelli has good arguments the sample is representative for the US states, it is not clear to me that it is in addition also representative for "all disciplines." The term "test the hypothesis" might just be more commonly used in some fields, e.g. medicine, than in others, e.g. physics. The thing is that in physics what is actually a negative result often comes in the form of a bound on some parameter or a higher precision of confirming some theory. Think of experiments that are "testing the hypothesis" that Lorentz-invariance is broken. There's an abundance of papers that do nothing than report negative results and more negative results (no effect, nothing new, Lorentz-invariance still alive). Yet, I doubt these papers would have shown up in the keyword search, simply because the exact phrase is rarely used. More commonly it would be formulated as "constraining parameters for deviations from Lorentz-invariance" or something similar.

That is not to say however I think there's no bias for positive results in physics. There almost certainly is one, though I suspect you find more of it in theoretical than in experimental physics, and the phrase "testing the hypothesis" again would probably not be used. Thing is that I suspect that a great many of attempts to come up with an explanation or a model that, when confronted with the data, fails, do never get published. And if they do, it's highly plausible that these papers don't get cited very much because it's unlikely very many people will invest further time into a model that was already shown not to work. However, I would argue that such papers should have their own place. That's because it presently very likely happens that many people are trying the same ideas and all find them to fail. They could save time and effort if the failure was explained and documented once and for always. So, I'd be all in favor of a journal for "models that didn't work."

Cosmic Strings

The appeal of string theory is in the simplicity of the idea. The devil, as usual, is in the details that follow. But one-dimensional objects are common in physical systems, and sometimes have little to do with string theory as the candidate theory of everything. The Lund string-model for example is an effective description for the fragmentation of color flux-tubes resulting in hadronization. And then there's cosmic strings.

Cosmic strings are stable, macroscopic, one-dimensional objects of high energy density that might be created in the early universe. It was originally suggested by Kibble in 1976 that such objects could form from symmetry-breaking phase transitions in quantum field theory that would take place when the universe was young and hot. These strings then form a network of (infinitely) long strings and loops that evolves with the expansion of the universe. It was thought for a while that strings might seed the density perturbations leading to the large-scale structures we see today, but this turned out not be consistent with the increasingly better data. While we know now that cosmic strings cannot have dominated in the early universe, some of them might still have been present, and still be present today.

The topic raised to new attention when it was found that cosmic strings might alternatively also be created in a string theory scenario in the early universe and then grow to macroscopic sizes. That is interesting because cosmic strings have a bunch of possibly observable consequences. For the purposes of testing string theory, the question is of course if one could distinguish a cosmic string created by ordinary quantum field theory from a cosmic super-string-theory-string.

Two of the most outstanding observables are that cosmic strings create peculiar gravitational lensing effects and can, while they move around, create cusps that release bursts of gravitational waves. There are other, more subtle, signatures, such as the creation of small non-Gaussianities in the cosmic microwave background (CMB) and some influence on the CMB tensor-modes, but the gravitational lensing and gravitational wave bursts have so far gotten the most attention due to the already good experimental prospects of detecting them.

For what the lensing is concerned, every now and then a candidate is found where the lens might have been a cosmic string, though none of them has survived scrutiny. Like CSL-1, that later turned out to be merely two similar galaxies in close vicinity. In any case, the gravitational lensing wouldn't allow us to tell whether we're looking at a super-string or not.

There are however differences between fundamental and non-fundamental cosmic strings that have been pointed out during the last years. These stem from the presence of additional spatial dimensions in super-string theory. These have the consequence of altering the evolution of the string network, resulting in a denser network today, that might give one the hope that bursts of gravitational radiation are more likely to occur. Recently though, a more detailed study has been done, examining the motion of the string and the gravitational radiation emitted by taking into account the additional dimensions:

Effect of extra dimensions on gravitational waves from cosmic strings
By Eimear O'Callaghan, Sarah Chadburn, Ghazal Geshnizjani, Ruth Gregory, Ivonne Zavala
Phys. Rev. Lett. 105:081602 (2010).
arXiv:1003.4395 [hep-th]

In their analysis, the researchers found that the presence of compactified extra dimensions larger than the width of the string dampens the gravitational wave emission. The effect depends on the the number of extra dimensions, and the damping can be several orders of magnitude. While this is interesting in the sense that the signal carries information about the sort of string one is dealing with, it means unfortunately that the signal is also far less likely to be detected at all. The strength of the damping depends also on the ratio of the width of the string and the size of the extra-dimensions, though this dependence is hidden within the model and not obvious from the results. I wrote to one of the authors of the above paper, Ruth Gregory, and was explained that simulating the dynamics of a thick string was quite a challenge which is why they had to resort to an empirical model.

A signal of cosmic strings would be tremendously exciting either way. But so far the prospects of being able to unambiguously assign such a signal to string theory seem slim.

From IGNobel to the Nobel Prize

Congratulations to Andre Geim of the University of Manchester, the first winner of both the IGNobel and the Nobel Prize in Physics!

Back in 2000, Andre Geim shared the IgNobel Prize with Sir Michael Berry, for his celebrated levitating frog eperiment.

Today, ten years later, he has been awarded the Nobel Prize in Physics for 2010, together with Konstantin Novoselov, for "for groundbreaking experiments regarding the two-dimensional material graphene".

Graphene, as this chicken-wire single-atom carbon layer is called, is a cool material for theorists and experimentalists alike - just have a look at Google to see how popular and important this stuff has become.

It seems to me that the way how Geim and Novoselov discovered graphene in 2004 by using adhesive tape to peel a single layer of carbon atoms off a piece of graphite - the "Scotch tape method" - and the levitating frog clearly show the same playful attitude towards physics, a great way to do science!

---

For a first reading about Graphene, check out Carbon Wonderland by Andre Geim and Philip Kim, Scientific American April 2008, and Graphene: Exploring Carbon Flatland by Andre Geim and Allan MacDonald, Physics Today 60 (2007) 35-41.

More technical papers can also be found on the website of Geim's group at Manchester.

TAGS: PHYSICS NOBEL PRIZE, GRAPHENE

Einstein on the discretenes of space-time

I recently came across this interesting quotation by Albert Einstein:

“But you have correctly grasped the drawback that the continuum brings. If the molecular view of matter is the correct (appropriate) one, i.e., if a part of the universe is to be represented by a finite number of moving points, then the continuum of the present theory contains too great a manifold of possibilities. I also believe that this too great is responsible for the fact that our present means of description miscarry with the quantum theory. The problem seems to me how one can formulate statements about a discontinuum without calling upon a continuum (space-time) as an aid; the latter should be banned from the theory as a supplementary construction not justified by the essence of the problem, which corresponds to nothing “real”. But we still lack the mathematical structure unfortunately. How much have I already plagued myself in this way!”

It's from a 1916 letter to Hans Walter Dällenbach, a former student of Einstein. (Unfortunately the letter is not available online.) I hadn't been aware Einstein thought (at least then) that a continuous space-time is not “real.” It's an interesting piece of history.

Experimental Search for Quantum Gravity - Workshop Summary

With some delay, here's finally the summary of our summer workshop on Experimental Search for Quantum Gravity. Most of the delay is due to the videos only having been uploaded two weeks ago, but you can now find the link to the recording and slides on the conference website.

The phenomenology of quantum gravity is a still fairly young research field, and it is good to see it is attracting more interest and efforts every year. Experimental test, also in form of constraints, is an important guide on our search for a theory of quantum gravity. The challenge is that gravity is such a weak force compared to the other interactions, which has the consequence that quantum effects of gravity are extremely difficult to detect - they become important only at the Planck scale, at energies 16 orders of magnitude above what the Large Hadron Collider (LHC) will reach. However, during the last decade proposals have been put forward how quantum gravity could be testable nevertheless.

To that end, a number of models have been developed that arguably are at different levels of sophistication and plausibility, not to mention man-hours. As you can guess, this makes the field very lively, with many controversies still waiting to be settled. So far, none of these models have actually been rigorously derived from a candidate theory of quantum gravity. Instead, they are means to capture specific features that the fundamental theory has been argued to have. Such phenomenological models should thus be understood as simplifications, and one would expect them to be incomplete, leaving questions open for the fundamental theory to be answered.

The best place to look for quantum gravitational effects is in regions of strong curvature, that would be towards the center of black holes or towards the first moments of the universe. Since black hole interiors are hidden from our observation by the horizon, this leaves the early universe as the best place to look. It is thus not surprising that the bulk of effort has been invested into cosmology, most notably in form of String Cosmology and Loop Quantum Cosmology. The typical observables to look for are the amplitudes of tensor modes in the cosmic microwave background (CMB) and non-gaussianities.

The other area of quantum gravity phenomenology that has attracted a lot of attention are violations and deformations of Lorentz-invariance. These have been argued to appear in many approaches towards quantum gravity, including Loop Quantum Gravity (LQG), String Theory, Non-commutative geometry and emergent gravity, thus the large interest in the subject. However, the details are subtle. As I mentioned, no actual derivation exists from either LQG nor string theory, so don't jump to conclusions. Violations of Lorentz-invariance, which have a preferred restframe, can be captured in an effective field theory and are testable to extremely high precision with particle physics experiments (both collider and astrophysics) that allows us to tightly constrain them despite the smallness of the Planck scale. Deformations of Lorentz-invariance have no preferred frame and have been argued not be expressible as effective field theories, thus evading the tight constraints on Lorentz-invariance violations. Deformations of Lorentz-invariance generically lead to a modification of the dispersion relation and an energy-dependent speed of light, which may be observable in gamma ray burst events. As you know from my earlier writing, there's some discussion at the moment about the consistency of these models, and Lee Smolin gave a nice talk on that. Giovanni Amelino-Camelia summarized some of the recent work on the field, and added an interesting new proposal.

Besides these areas into which most of the work has been invested, there's a number of interesting models based on ideas about the fundamental structure of space-time. There is, for example, the causal sets approach, which is Lorentz-invariant, yet results in diffusion, aspects of which may be observable in the CMB polarization, which Fay Dowker spoke about at the workshop. Again, note however that the diffusion equation is motivated by, though not yet actually derived from, the causal sets approach. Then there's the quantum graphity models which I personally find very promising. Unfortunately, Fotini Markoupoulo could not make it to our meeting. I am reasonably sure though that we'll hear more about that model and its phenomenological implications in the future. And there's models about space-time foam leading to decoherence and/or CPT violation, models about space-time granularity leading to modifications of Eötvös' experiment (preprint here) - and I won't attempt to make this a complete listing because I'll inevitably forget somebody's pet model.

A class of models that one should discuss separately are those with a lowered Planck scale. It can happen in scenarios with large extra dimensions that quantum gravitational effects are not actually as feeble as we think they are from extrapolating the strength of gravity over 16 orders of magnitude. (For details, see my earlier post on such models.) It might instead be the Planck scale is just around the corner, making it accessible for collider experiments. A lot of work has been done in this area and these models are now up to being tested at the LHC. Thomas Rizzo gave a great talk on these prospects, and Marco Cavaglia spoke about the production of mini black holes in particular.

Then there's the possibility that we do already have observational evidence for quantum gravity, we just haven't recognized it for what it is. Stephon Alexander talked about a model that generates the neutrino masses, the cosmological constant, and makes additional predictions. Can you ask for more? (Preprint here.) And Greg Landsberg gave a talk about his recent work, trying out the idea that on short scales space-time is not higher- but lower-dimensional (preprint here). This idea has been around for some years now (even New Scientist noticed), but in my impression it so far lacks a really good phenomenological model.

We had three discussion sessions during the week. One on the question what principles might be violated by quantum gravity, one on experiments and thought experiments, and one on the future of particle physics. Unfortunately the recording of the last one, which was the most lively one, failed, but check out the other two. The discussions went very well, and I think they served their purpose of people getting to know each other and exchanging their opinions about the central questions of the field.

All together, I am very pleased with the workshop. Despite a number of organizational glitches, it went very smoothly. The experimentalists mixed well with the theorists, we covered a fair share of the relevant topics, and it didn't rain on the BBQ. To offer some self-criticism, we did this year have a lack of string phenomenology. Some may want to count Mavromatos as "stringy," but we didn't have anybody speaking on string cosmology for instance. That was not by design, but by chance, since, as usual, some of the people we invited declined or could eventually not make it. One of the lessons that I personally have drawn from this workshop is that there is some degeneracy in the predictions of various models that should be sorted out by combining several predictions. This has been well done in the case of extra dimensional models where a clear distinction between signatures of different scenarios has been invested a lot of effort into. Similar studies are however missing when it comes, for example, to quantum gravity phenomenology in the early universe as predicted by different models.

In any case, I hope that we will have more workshops in this series in the future. I'll keep you posted. And I'm sure, one day the workshop will come when we'll actually have evidence to discuss...

Discovery or Invention?

Some years back I was shortlisted for a job and gave a seminar, doing my best to leave a good impression. In the questions following my talk, somebody asked if I think the process of science is one of discovery or one of invention. "Both," I said, leaving everyone in the audience, including myself, somewhat confused.

In more detail, the question is the following. In the process of science, we accumulate knowledge. That's observations, that's applications, that's theories. But this knowledge, does it exist before we have made it our own and it is just up to us to discover it? Or is this knowledge genuinely new, and does only come into existence once we are thinking about and working with it?

If one goes down this slope it can becomes somewhat slippery, and you might end up at the question whether all of science is a human construct, tainted by the biases of our consciousness and social effects (invention) - or if science in its essence, ideally, is pure and objective, without human baggage (discovery). You don't have to slide down the slope though, because going there neglects that either way we're doing our best to make science as useful for our purposes as possible, trying to reduce biases and social effects.

Take for example quantum field theory. If you believe that mathematics has an existence independent of human consciousness, you would argue that quantum field theory existed before we knew of it, and we discovered and then used it. If you don't believe that Plato's world of ideas is real, then you'd instead call it an invention of the human mind. Or take some application like for example the LASER (that just celebrated its 50th birthday). Was the construction of such an instrument always a possibility that existed, and it was just discovered by humans? Or is it an invention, a possibility that only came into existence thanks to our ingenuity?

This admittedly philosophical question, that is eventually one about the meaning of creativity, has a correspondence in the arts. In interviews, I've sometimes found painters or writers saying that the "idea" for their work was waiting for them, they were just the ones who brought it to paper or canvas, they are the discoverer and the medium to bring it into our attention, but not the inventor. Some even speak of a mental "place" that they visit to find their ideas, a place they apparently believe is not a creation of their own mind. Others however describe the creative process as entirely self-made, often including trial and error, many studies and improvements, the making of something genuinely novel that has never existed before, an invention.

I, as many physicists I think, believe that reality exists independent from us. It is thus out there for us to discover. Reality doesn't care about the quirks of the human brain or or problems of our societies. So that would put me on the side of the discoverers. However, it is not that simple. Whatever we do, our discoveries are shaded by human perception. Whatever we observe, we observe it with human senses or human instruments. And the theories we write down, they are stories that humans tell which are meant to describe the real world, rather than actually being the real world. To illustrate that, let me recycle an image I used in my earlier post on Models and Theories, see left. You first need to discover. But once you measure it, once you write it down, and make it suitable for human use, you're creating an - necessarily imperfect - image, may that be a collection of data points or a theory. And that's the part of the process which is an invention.

I would argue for example that while we have discovered quantum mechanical effects which exist somewhere in "the real world out there," the theory we have to explain them is a human construct, it's an invention. It uses variables and language that are specific to our species, it carries the history of particle-wave duality, it is suitable to describe the data that we have measured with our devices. An alien civilization might discover the same effects, but they might invent a different story to explain them, a theory that explains their data in possible entirely different ways.

I don't even think that mathematics itself is free of human baggage, or that it will remain the best way to describe Nature if you could fast forward some hundred thousand years. We just think today it is because we cannot possibly imagine anything else that would work better. But I think we should always keep in mind the Principle of Finite Imagination: Human imagination has limits set by our cognitive abilities. Excluding a possibility because we cannot today imagine it neglects that time may bring significant changes to our cognition or species.

I didn't get the job. I doubt it had anything to do with my inability to explain my reply to this particular question. But still, I wished I had been able to express myself better back then.

Now it's your turn: Discovery or Invention?