## Tuesday, September 30, 2008

### Hugging the Sheep

My recent twitter status "Bee has hugged the sheep" apparently confused some followers, so here is the sheep:

It's made of wood with ears of leather and really sheepy fur.

It was a birthday present the year before I left Germany and stayed with Stefan. The sheep is always happy when I visit. And here is Stefan, featuring his new Google T-shirt in honor of Google's 10th birthday:

## Sunday, September 28, 2008

### The Variational Principle

Lawns in public places all suffer from the same problem: people don’t like detours. In cities throughout the world people search for the fastest route to the workplace, the shortest way to the restroom, the least pricey airline, the most convenient parking spot - depending on resources and personal preferences we optimize our day with regard to criteria we regard important. Cooks experiment with recipes to create the most delicious meals, politicians argue about taxation to score in polls, you aim to find the most comfortable position on your couch. In most cases, these are optimizations through incremental modifications and evaluation of the change, little steps of trial and learning, and eventual selection of the optimal solution.

Not only our daily lives reflect our aim to optimize under variation, but Nature itself shows the selection of optimal configurations. A soap bubble minimizes surface area [1]. Electric currents prefer the way of least resistance, water runs downhills around obstacles in its way.

In all cases we have a system with a quantity which is optimized for one of many possible configurations, and the configuration optimal in this regard is the one realized in Nature. Optimization can mean either lowering a quantity to a minimal value, or obtaining a maximal value. Might that be you slouching on the couch with your feet on the table because it’s the most comfortable way to spend your evening, or dozens of students trampling their traces in the campus’ lawn because it’s the fastest way to coffee.

The same idea underlies theoretical physics. For every system we want to describe we have a quantity whose value has to be optimized. The way we find the optimal configuration is to make small changes and to take the configuration which would get less optimal under any change. This is essentially the same procedure one does for finding the extrema of a function by requiring the first derivative to vanish: These small changes are called ‘variations’, are denoted with a small delta δ, and the process is called the ‘variational principle’. For the optimal configuration, the variation has to vanish. In physics, in most cases the quantity optimized is called the ‘action’, and is usually denoted with a capital S. The requirement then reads

The Best of all Possible Worlds

One can’t write about the variational principle without some name dropping. The first to drop is Gottfried Wilhelm Leibniz, German scientist, philosopher, mathematician, and the one with the cookie. Leibniz already in 1710 wrote the “Essais de Théodicée sur la bonté de Dieu, la liberté de l'homme et l'origine du mal ” (Engl: Essays of theodicy on the goodness of God, the freedom of man and the origin of evil, writing in French was apparently chique in the 18th century), in which he develops the thought that our world is the ‘best of all possible worlds’. Though his argumentation is heavily theological, he made fairly clear that with the ‘best’ world he meant one that is optimal in some sense, possibly in a sense not immediately obvious for us, and that the optimal world has to be among the indeed possible worlds. Certainly, we can imagine a world with less evil, less hunger, less poverty and less spam in my inbox, but is this a possible world? The question touches on the trouble with all utopias that build upon idealized caricatures of men, and remain wishful thinking because they fail to describe reality.

Voltaire famously made fun of the idea the world could as it is be optimal in his satire “Candide, ou l'Optimisme,” in which he attacks the Leibnizian optimism. This always seemed odd to me since I find Leibniz' conviction the world we live in is the best possible one rather pessimistic.

Leibnitz however inspired Maupertuis, a French mathematician and philosopher, to put the linguistic argument on a more rigorous base. Maupertius came up with the concept that light travels on the shortest path, known as Maupertius' principle, which was a successor of Fermat's principle and the predecessor to the principle of least action. The calculus of the general variational principle was only shortly after this developed by Leonard Euler and Joseph-Louis Lagrange. Both of their names are today intimately connected with the formalism: the equations of motions one derives from the variation are known as the ‘Euler-Lagrange equations’, and the action is an integral over a function called the ‘Lagrangian’ (though certain people insist on calling it ‘Lagrangean’).

Examples

The Lagrangian for Newtonian mechanics for example is
A nicer example is however the Lagrangian for a point particle of mass m in a possibly curved background described by the metric tensor gμν, where the action is just the length of the curve

The equation of motion is then the so-called geodesic equation, the shortest curve in an arbitrary background, which is not usually – as in flat space, e.g. a lawn – just a straight line:

The routes of airplanes for example are to a good approximation geodesics of a sphere (neglecting wind and countries who have issues with their airspace). Though it might not look like it on the routemap you find in the in-flight magazine, these are indeed the shortest connections possible.

For fields instead of single particles, the Lagrangian is a function over space-time and the action is a volume integral. The Lagrangian of General Relativity for example is just the curvature scalar R, the variation yields Einstein’s Field equations. The Lagrangian of free Electrodynamics is F2, where F is the field-strength tensor, the variation yields the free Maxwell equations. One can couple these to matter in a straight-forward way to also get the source terms.

One thing that is important to notice here is that these variations are not actual changes of the real system. Unlike you trying several non-optimal ways to your new workplace before you find one that you like best, here the variation is not performed in reality. It is a variation in the space of could-be configurations, a procedure to find the one realized. The world wasn’t created crappy and then became better, it was just optimal all along. Systems solve the equations one obtains from the variational principle, they don’t learn how to do so as time goes by.

So, now that we've talked about the ‘best’ world, let us replace ‘best’ with ‘fittest’...

Cosmological Natural Selection

Cosmological Natural Selection (CNS) is Lee Smolin’s suggestion for a testable alternative to the anthropic principle (see hep-th/0612185). You find my thoughts on the anthropic principle here, in brief: The (weak) anthropic principle is a nothing but a constraint on the parameters of our theories. It is trivially correct our universe allows the existence of life (we can discuss whether the life we know is intelligent or not), and thus whatever model we use better were not in disagreement with that. This can indeed provide constraints on the parameters of your theory. However, if your theory can’t accommodate the requirement you’d not throw out the assumption life is possible in our universe, but rather your theory.

The most severe problem with the anthropic principle is that a mathematically useful definition of life is absent, and the presence of life is not something that anybody has yet managed to quantify. Thus, it is not a scientific argument, but a rhetoric one and it’s for practical purposes useless. However, as Lee points out correctly (in his paper and also in his recent talk at the Multiverse conference, see PIRSA 08090050) anthropic arguments typically have nothing to do with life in the first place, but with some more general preconditions such as formation of galaxies or existence of carbon molecules, which can then indeed be scientifically evaluated.

CNS tackles the question why our universe is as it is essentially by suggesting a quantity that is optimized for our universe with the parameters that we observe. The specific quantity in this case is the number of black holes and Lee’s argument goes that the number of black holes would drop whenever one turns the parameters of our theories - one can apparently study a lot of different scenarios where that holds. However, as it stands this quantity, the number of black holes, unfortunately is also ill-defined. The obvious questions lying at hand are: If N black holes merge does that count as one or as N? What if a black hole evaporates? Do virtual black holes count?

But forget for a moment the number of black holes specifically and take any quantifiable function of the parameters in the Standard Model and ΛCDM. Then the idea is simply our universe with the parameters as we have measured them optimizes this quantity. Turning the parameters to see whether the number increases or decreases is a poor man’s way to finding a maximum, so pretty much a variational principle.

That doesn’t quite explain though why that scenario is called something-with-natural-selection. The reason for this I suspect is a severe case of Santafeism, and that’s where the idea stops making sense to me. See, the black holes, they supposedly don’t have singularities inside but form new ‘baby universes’ with slightly modified parameters, and in such a way the ‘fittest’ universe, i.e. the one with most black hole offspring, is the one we’d likely find ourselves in. That baby-universe story sounds cute, but is as far as I am concerned wishful thinking.

But again, forget for a moment also the story with the baby universes.

What remains is the idea that we live in the “best of all possible worlds” in some sense. Might that be the “best” world to produce black holes or something else. The question here is simply whether there exists a quantity that is optimized for exactly the parameters of the Standard Model + ΛCDM that we observe in our universe. It lies at hand to think of complexity as a possible alternative, but here again one runs into the problem that it is not a well-defined quantity (what’s the complexity of planet Earth?) and thus useless for practical purposes. It remains the question however, whether the non-optimal worlds “really” exists.

I’m not a big fan of CNS because of the problems mentioned above (and some others), but I like the general idea that the function to be optimized might be a macroscopic quantity that is not easily derivable from the fundamental laws.

A Principle of Everything?

The variational principle has proved to be enormously useful and successful. In addition to that it is also a compelling, simple and elegant formulation. It has everything a theoretical physicist desires. Nevertheless, I can’t but occasionally wonder what if this principle does not indeed hold for the yet to be discovered unified fundamental laws that govern our universe?

Neither Einstein nor Maxwell initially formulated their theories starting from a Lagrangian, they started with the field equations. Yet at some point during the last century, it has become a standard procedure to start from the Lagrangian [2], which reduces the space of possible theories as there are indeed equations of motions that do not follow from any Lagrangian. Given that the examples I know are not examples I’d consider particularly interesting, this might not be a big loss. But the existence of a Lagrangian is nevertheless an implicit assumption that not typically is much discussed.

Sensemaking

The principle of least action appeared on our curriculum in my second year at College, and it has to me always been the most beautiful explanation of the world around us. Not only is the idea of optimization compelling, but the same principle can be used for completely different systems, and for different theories. The only thing one needs to change is the function to be optimized. With that function, you perform the variation according to a well-defined mathematical procedure and get the equations of motions. What a relieve that was to eventually have a clear procedure to arrive at the relevant equations after we had spend years in physics assembling equations on a case-by-case basis! Textbooks frequently offered explanations that only made sense if you already knew the result, it typically involved a lot of guessing and hand-waving, or knowing where to find the solution to the exercise. Now suddenly that all made sense.

More about the history and applications of the variational principle in this nicely illustrated book:

The Parsimonious Universe: Shape and Form in the Natural World
By Stefan Hildebrandt and Anthony Tromba

[1] An optimization that heavily inspired Frei Otto's architecture, who for example designed the Olympia Stadium in Munich. See e.g. The lightweight champion of the world - How soap bubbles and cobwebs helped Frei Otto win architecture's greatest prize, by Jonathan Glancey.
[2] Rspt. some decades later the path integral.

Lee Smolin (2006). The status of cosmological natural selection arXiv

## Friday, September 26, 2008

### The Cepheid Galactic Internet

Sometimes, I like to imagine all the electromagnetic waves around me, emails and phone calls in transit carrying message of joy or anger all around the world. These days, a wireless can be found almost everywhere, all you need is a laptop with a network card - “all you need” is an incredibly sophisticated electronic toy that only half a century ago would have been impossible to produce, would have been called science fiction, if not fantasy.

When I was a kid, I liked to imagine one day I'd build a device to receive the alien communication in the universe. Because, without doubt, if there's aliens somewhere they would send messages all through space. It occurred to me later they probably wouldn't broadcast all through the universe and the earth being in the line of their signal seemed rather unlikely.

Anyway, there are other ways one can imagine how alien civilizations could leave messages, possibly especially for less advanced civilizations - like us - to provide hints for boosting technological development and hopefully scientific insights. Jaron Lanier e.g. speculates that aliens might rearrange the stars, so we should probably go look for unusual star constellations. Hsu and Zee go one step further to suggest the creator of the universe himself could have left a message in the CMB. (We already found it.) The most recent contribution on this matter is

The Cepheid Galactic Internet
By John G. Learned, R-P. Kudritzki, Sandip Pakvasa, and A. Zee
arXiv:0809.0339v2

In this paper the authors suggest that alien civilizations would use modulation of Cepheid variable stars to encode their message. Chepheid variable stars are well known for a fairly tight correlation between their period of variability and their absolute luminosity, which makes them ideal candidates to determine distances. Cepheids are giant yellow stars with a luminosity about a thousand times that of the sun and are easily observed. The authors thus “expect that any civilization undertaking astronomy would soon discover them.”

They further speculate that a modulation could be achieved by injecting a pulse of neutrinos into the stellar core where the deposit of additional energy would affect the exact period of oscillation. Such a modification of single periods however, they go on to explain, would likely go unnoticed in the commonly made Fourier analysis of the measured spectrum. Therefore, they suggest to reinvestigate the luminosity oscillations using a different analysis method that would allow to discover the alien message over the periodic signal (and possible noise).

They close with saying
“We propose that there may well be signatures of [extraterrestrial intelligence] communication available in data already recorded, and that a search of Cepheid [...] records may reveal an entre into the galactic internet!

It may be a long shot, but should it be correct, the payoff would be immeasurable for humanity. The beauty of this suggestion seems to be simply that the data already exists, and we need only look at the data in a new way.”

A long shot indeed. Science fiction, fantasy? But isn't it nice to imagine the answer to our questions might be in the stars quite literally?

A nice weekend to all of you!

## Wednesday, September 24, 2008

### Web Science

The last few days I've been working at home, waiting for my husband to return from work. I'm feeling very housewifey, noticed he bought an electric toothbrush, and evidently let himself be talked into an abonnement not only of Bild der Wissenschaft, but also of Scientific American. So I got to read today the October issue of Scientific American, the cover features the “Big Bounce” also known as Martin Bojowald. What caught my eye however were not the happily bouncing universes on the cover, but an article by Tim Berners-Lee - inventor of the world wild web - and Nigel Shadbold, who is a professor of artificial intelligence at the University of Southampton. They write about the emergence of a new discipline called “Web Science”. The online version has a different title, but is available here

“This new discipline will model the Web’s structure, articulate the architectural principles that have fueled its phenomenal growth, and discover how online human interactions are driven by and can change social conventions. It will elucidate the principles that can ensure that the network continues to grow productively and settle complex issues such as privacy protection and intellectual-property rights. To achieve these ends, Web science will draw on mathematics, physics, computer science, psychology, ecology, sociology, law, political science, economics, and more.”

Which sounds to me pretty much like a subsector of Network science, just confined to the online world. They have created a research initiative, called the

which is a joint endeavour between the Computer Science and Artificial Intelligence Laboratory (CSAIL) at MIT and the School of Electronics and Computer Science (ECS) at the University of Southampton.

With this as with so many interdisciplinary approaches I wonder whether it will go anywhere in the long run. In this case however, I welcome that they have formulated a clear direction:
“The goal of WSRI is to facilitate and produce the fundamental scientific advances necessary to inform the future design and use of the World Wide Web.”

## Monday, September 22, 2008

### This and That

• Submissions are currently being accepted for OpenLab 2008, the anthology of the best science-blog writing of 2008.

• Philip E. Bourne et al's 10 simple rules for getting published, for getting grants, for organizing a scientific meeting (should have paid more attention to rule #3), for selecting a postdoctoral position (Quote: “For a future in academia, the most tangible outcomes are publications, followed by more publications [...] Strive to have at least one quality publication per year.” - is exactly the kind of advice that turns science it into a paper production factory, thanks so much, just what I needed). And more simple rules for a successful collaboration (applying rule #7 early protects me very efficiently from any kind of collaboration), and for graduate students (lots of nice words).

• From the Science Blogging 2008 conference, organized by NatureNetwork, originated the 'Science Blogging Challenge': “to persuade a senior scientist to start writing a blog. One prize will be to be featured in next year’s Open Lab 2008 – the best of science writing on the web. The other prize – which caused an extensive collective intake of breath – will be an all expenses paid trip to Scifoo next year for both blogger and the encourager.” [Via Shirley]

• Quotation of the week:

“Too many of us look upon Americans as dollar chasers. This is a cruel libel, even if it is reiterated thoughtlessly by the Americans themselves.”
~Albert Einstein

## Sunday, September 21, 2008

### 100 Years of Space-Time

Die Anschauungen über Raum und Zeit, die ich Ihnen entwickeln möchte, sind auf experimentell-physikalischem Boden erwachsen. Darin liegt ihre Stärke. Ihre Tendenz ist eine radikale. Von Stund' an sollen Raum für sich und Zeit für sich völlig zu Schatten herabsinken und nur noch eine Art Union der beiden soll Selbständigkeit bewahren.

Hermann Minkowski, opening words of his talk "Raum und Zeit" at the 80. Meeting of Natural Scientists and Physicians, Cologne 1908 (English translation see footnote).

Hermann Minkowski, 1864-1909 (from MacTutor History of Mathematics Archive)
September 21, 1908, was a wonderful and sunny late-summer Monday in Cologne, Germany, where scientists from all over the country had come together for the 80th General Meeting of the Society of Natural Scientists and Physicians.

On that day, Hermann Minkowski, a well-known mathematician from Göttingen, gave a talk with the title "Raum und Zeit" – "Space and Time". In this now famous talk, Minkowski proposed a new formulation of the special theory of relativity. His formulation implied a unification of the notions of space and time, which traditionally have been seen as completely independent, to a four-dimensional entity dubbed "space-time".

Points in this "space-time" correspond to "events", e.g. things happening at a certain time and at a certain point in space, and Minkowski proposed to define a distance between events x (at time t and location x, y, z) and x' (at time t' and location x', y', z') by

distance(x, x') = c²(tt')² − (xx')² − (yy')² − (zz')²,

where c is the speed of light. The distance between two events defined in this way is, according to the special theory of relativity, the same for all observers in uniform relative motion, or, using the technical jargon, does not change under Lorentz transformations. This definition is a generalization of the Euclidean distance between two points in space, which does not change ("is invariant") under rotations, and the corresponding four-dimensional space-time is now called "Minkowski space".

All the concepts we now use to describe the kinematics of special relativity – events, worldlines, light cones – were presented in front of a large public audience for the first time one hundered years ago today, in Minkowski's lecture.

Future ("Nachkegel") and past ("Vorkegel") light cones, and timelike ("zeitartiger") and spacelike ("raumartiger") vectors in the writeup of Minkowski's talk (page 82 of Raum und Zeit, Jahresbericht der Deutschen Mathematiker-Vereinigung 18, 1909).

Worldline ("Weltlinie") of a particle in Minkowski spacetime (page 86 of Raum und Zeit).

Hermann Minkowski was born in Lithuania, and had studied mathematics at the University of Königsberg. His contributions to number theory, complex analysis and algebra had made him quite renowned at a young age, and he held positions as professor of mathematics at the universities of Bonn, Zürich (the ETH), and Göttingen. At Göttingen, he shared the interest of Hilbert in the problems of the theory of the electron and special relativity.

Curiously, his worldline hat crossed that of Albert Einstein before: Einstein, as a student of physics at Zürich, had been taught mathematics by Minkowski. But it seems that Minkowski didn't have a very good impression of his student. On the other hand, Einstein had some difficulties to make sense of the reformulation of his theory by his former teacher. Arnold Sommerfeld quotes Einstein as having said in reaction to Minkowski's work that "since the mathematicians have invaded the theory of relativity, I do not understand it myself anymore."

But it's clear that Minkowski's four-dimensional world was an essential conceptual step in the understanding of relativity, and indispensable for the later formulation of general relativity. Unfortunately, Minkowski didn't live to see or even foster these developments. His lecture on "Space and Time" was his last scientific work – he died from a ruptured appendix in January 1909, at the age of 44.

The views of space and time which I wish to lay before you have sprung from the soil of experimental physics, and therein lies their strength. They are radical. Henceforth space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality.

Translation by W. Perrett and G.B. Jeffery, taken from Hermann Minkowski, "Space and Time", in Hendrik A. Lorentz, Albert Einstein, Hermann Minkowski, and Hermann Weyl, The Principle of Relativity: A Collection of Original Memoirs on the Special and General Theory of Relativity (Dover, New York, 1952), pages 75-91.

For more about Minkowski and his role in special relativity, see e.g. L Corry: Hermann Minkowski and the postulate of relativity, Arch. Hist. Exact Sci. 51 (1997), 273-314 (a free preprint as PDF is here), and Scott Walter: Hermann Minkowski’s approach to physics, Math Semesterber. 55 (2008) 213–235 (preprint as PDF), and Minkowski, Mathematicians, and the Mathematical Theory of Relativity, in H. Goenner, J. Renn, J. Ritter, T. Sauer (eds.): The ExpandingWorlds of General Relativity (Einstein Studies 7), Boston/Basel: Birkhäuser 1999, 45–86 (preprint as PDF).

## Friday, September 19, 2008

### Villa Bosch

The workshop about which I wrote yesterday takes place at the Villa Bosch, East of Heidelberg's city center up on the hills with a great view across the river valley. It is a very pittoresk location. You find some info about the history of the villa on their website: it was erected in 1921 for the CEO of BASF, Carl Bosch, who was awarded the Nobel Prize in Chemistry 1931. Here are some photos I just took during the coffee break:

The workshop is not in the villa itself, but in the 'studio' right next to it, a modern building with lots of glass and light wooden panels. I couldn't find a sensible angle to get a shot of the building, but here's how it looks from the inside:

(Click to enlarge photos)

## Thursday, September 18, 2008

### Parallel Worlds

Coming back to Germany always feels weird. These first some days I will turn around after people thinking “Hey, they speak German!” I search for German translations of English words waving my arms wildly, I forget to order water with dinner, and make right turns at red. Speaking of driving, how can somebody possibly make sense of this mess of street signs? Heck, I've grown up here and don't know what to do. Worse, why do streets constantly end unexpectedly, or turn into one-way-streets, and either way just never get you to where you wanted to go? So much about charming old city centers. I don't even want to start with the Autobahn. These Germans, they drive like nuts, change three lanes without a signal to make the next exit.

I step into a plane and swap my circle of friends. Yesterday I was busy organizing a conference, today I am searching for a wedding present. Yesterday I was cursing the late-summer humidity in Ontario, today night temperatures drop to freezing point. Yesterday I was trying to get a grip on cosmological perturbation theory, today I’m sitting in a group of people discussing the mortage crisis.

The workshop I’m currently at - excuse me, the “symposium” - is a different world. I’m surrounded by men in suits and a noticeable fraction of elegantly dressed women. We all have name signs on our tables, and more than half of the speakers read their talk off notes, sitting on the front table. One has to get used to the melody being different from talking freely, but it is much easier to follow the line of thought than trying to follow somebody stuttering incoherently his way though a powerpoint presentation. Nobody in the whole room uses a laptop during other people’s talk. I make a weak attempt to work on a draft while somebody speaks about the similarity of Gorillas to CEOs and feel like my typing hangs in the air like I’d just burped. So that’s why blogging is slow. One can only burp so much among suits.

A British guy in his sixties named Charles tells me he will mention the LHC in his talk and asks what Bose’s first name is. “I’m bad with names,” I say, “I’d ask Google.” – “Who?” Somebody else inquires what I do if I’m not working, and I mention I’m writing a blog - “What?” The guy next to me works on the emergence of musical trends, specifically that of the Hip-Hop wave in Germany and Italy and asks what I’m working on. Good question I think. Cosmology is what I say. He finds that complicated. I am sure the emergence of music trends is far more complicated than Einstein’s Field Equations. I think I’m the only one here with a background in the natural sciences.

“Learning Organizations” is the topic of this workshop – excuse me, symposium. I know nobody of the speakers, I know hardly anything about the topics, but it seems most of the other participants don’t know each other as well, except for the locals from Heidelberg. I would really like to know how can we adapt the institutions that we use to organize our lives to the challenges we are presently facing and that will become more pressing in the future. How can we upgrade our outdated systems so we can make fast decisions about complex problems when we have no time for trial and error? How can we efficiently incorporate expert’s knowledge? How can we break out of our fixed organizational structures and enable a more flexible handling of the way we reach decisions and implement them? I am hoping to learn something about that here.

So far, I am not sure admittedly what to make out of all these talks. I miss the lingo I am used to. Everybody seems to have a different perspective and a different point of view, and everybody is politely and nicely contributing and trying to find similarities. But what I’d want to hear is: hypothesis, model, assumptions, data, test, limits, uncertainties, conclusion. I’m wondering where the applications are, I’m wondering where the suggestions are, I’m wondering where the vision is. What I hear is how Gorillas are like CEOs. Here is why: A male Gorilla subject of aggression of a female Gorilla can’t afford to hit the female because he would lose his status in the group. Instead he will direct his aggression at the next male Gorilla in his vicinity, a risk for his status as well, because he will have to win the fight or again lose his status in the group. What that has to do with CEOs? It’s supposed to tell us something: emotions come before strategical thinking. It can result in an instant reaction with a random target and a suboptimal outcome.

The topic of the mortgage crisis keeps coming back. I don’t know nothing about economy so I should probably keep my mouth shut. Mpfgprrrrrrpfh. Ah. Okay, I tried. So here is my crisis explanation: Lacking negative feedback upon the emergence of nonsense. Too many people according to whose self-interests it made sense to carry on with what macroscopically didn’t make any sense at all. Too many people who believed they'd be smarter than all the other people. But most importantly: no place where the knowledge of that nonsense could have been directed to, lacking negative feedback, growing bubbles that had to burst. That combined with the different timescales the economical and the political system work on. The former enormously fast, and the latter lagging behind.

I offer this explanation when the discussion comes up again. A women remarks it’s more a question of power than of timescales. I can’t agree on that: There were many people who were not surprised by this crisis at all, some warned of it before, without effect. Had there been enough time, reason would have prevailed. Hey, Science is a Worldview! But so we had a system that wasn’t able to learn fast enough, institutions that were not able to adapt. And no, I don’t think that’s the end of the story.

Coffee break. You know what’s really scary is that people listen to me.

## Tuesday, September 16, 2008

### Physics: Spotlighting Exceptional Research

After a week full of talks discussing problems of information and knowledge management in the age of infotainment and information overflow, today I get an email from the APS announcing the launch of “Physics” (note the unique creativity of the name), a free online publication dedicated to “spotlight” what you really need to know, to put specialized papers in a broader context, and to provide reviews:
“Physicists are drowning in a flood of research papers in their own fields and coping with an even larger deluge in other areas of physics. The Physical Review journals alone published over 18,000 papers last year. How can an active researcher stay informed about the most important developments in physics?”

Yeah good question. By reading blogs maybe? ;-)

Either way, they offer three types of articles:
• “Viewpoints” are essays of approximately 1000–1500 words that focus on a single Physical Review paper or PRL letter and put this work into broader context.
• “Trends” are concise review articles (3000–4000 words in length) that survey a particular area and look for interesting developments in that field.
• “Synopses” (200 words) are staff-written distillations of interesting and important papers each week.

In addition, they intend to publish selected letters to the editor to allow readers a chance to comment on the commentaries and summaries.

My comment is that they've correctly identified the need to filter a vast amount of information in a sensible way, I welcome the effort very much and wish them good luck. They should do something about the title though, it's absolutely ungoogleable.

## Sunday, September 14, 2008

### My husband sent me these beautiful flowers...

... and I have to throw them in the garbage because I'll be away the next weeks. Well, I can't possibly give them to the neighbor, can I? So I'll take a photo with me instead.

## Saturday, September 13, 2008

### Science in the 21st Century: Summary

Last week's conference has been a tremendously interesting meeting that gave me a lot to think about. I am simply unable to briefly summarize it, especially since I'm already packing bags to head off for another workshop - oh, excuse me, it's called a "Symposium" not a workshop. So instead, I just want to tell you about yesterday's summary discussion, moderated by Michael Nielsen.

Michael picked three people and asked them to answer the following two questions:

1) What was the most striking thing you learned at this conference?
2) Will what you heard here make you change something in your professional life?

The people he selected were Chad Orzel, David Kaiser, and Garrett Lisi, who have quite a different background and lifestyle.

Chad said he was intrigued by John Willinsky's talk and by learning about the Public Knowledge Project. Chad's main concern is making scientific work more accessible, for the broader community as well as to the public, and this project has a lot potential in this regard. As to the second question, he found it very interesting to learn about the benefits of having an open lab notebook from Cameron Neylon's talk, and what other tools are out there. He said he had never thought of the open science movement as interesting but it seems worth looking into. It is attractive, so he said, not in a philosophical but in a hands-on way, and he might look into that closer.

David said that he came to this meeting thinking there is an absolute limit to how much of real interaction can ever be substituted by virtual communication channels, and that there is “some residual unanalyzable something” which could never be replaced. He was surprised to learn how much human interaction and collaboration meanwhile can take place online, and is wondering whether virtual interaction we will maybe asymptotically approach the real one. Regarding the second question he said he doesn't have a blog, and never reads blogs because he hasn't been convinced of the value in that before. But possibly he might reconsider...

Garrett explained he was thrilled to learn of Mendeley from Victor Henning's talk, and generally by the combination of people at the meeting, people who normally wouldn't interact. He further said that he used to think of journals as “dinosaurs that would eventually die out,” but Timo Hannay's talk shed a different light on the role of journals. If you haven't looked at Timo's talk, it is very recommendable and entertaining. Timo told us about the various ways in which Nature facilitate communication of science, both in and outside the community - a mission far beyond printing a magazine. Garrett further said Lee's talk gave him something to ponder, since he hadn't thought before of the social aspects of the scientific endeavor and the importance of the opinion building in the community.

As to me, I absolutely loved Eric Weinstein's talk and was surprised to learn how tall Chad is! I further heard so much about the merits of wikis that I've created one. Now I only have to convince my collaborators to also use it...

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### Sticky notes

Dull office? Here's a suggestion:

[Eepybird's Sticky Note Experiment from Eepybird on Vimeo]

Muchas gracias to Andi and a great weekend to all of you!

## Friday, September 12, 2008

### Science and Politics

I had the best intentions to write more about our ongoing conference on Science in the 21st Century, but I didn't fully realize how exhausting it can be if every talk at a meeting is interesting. I'm totally not used to that. Since I presently don't have the time to write much, let me just briefly tell you about a discussion we had yesterday afternoon, lead by Beth Noveck from the New York Law School. The question that we eventually focused on was

How can science can be more efficiently embedded into the politic decision making process?

Greg Wilson - referred to by Chad as "Ontario's fastest typer" - took notes of the discussion - the file is here. There were a couple of interesting thoughts that came up in the meeting. At some point Greg asked the crucial question: How many of you work less than 60 hours per week? Not a single hand went up.

I totally agree with him that a large part of the issue is that scientists getting involved in politics is not presently sufficiently appreciated to convince typically extremely busy researchers to spend time on it. Another part of the problem is one of organization. It is a recurring theme at this conference: how do we get knowledge to where it needs to be and communicate it appropriately?

I'd just like to pass on these questions to you. I'd be really interested to hear your opinion on this.

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## Tuesday, September 09, 2008

### Black Holes at the LHC - and again

I just noticed that yesterday we had twice as many visitors as usual and looked at the recent keyword activity that leads people to this blog. Here is a sample

9 Sep 06:46:47 AM www.google.com.au -- black holes from lhc
9 Sep 06:43:17 AM search.yahoo.com -- recreating the big bang experiment
9 Sep 06:38:10 AM www.google.co.uk -- cern lhc recreate big bang black hole
9 Sep 06:36:56 AM www.google.co.uk -- micro black hole
9 Sep 06:34:57 AM search.yahoo.com -- recreating big bang
9 Sep 06:33:30 AM www.google.co.uk -- lhc black holes
9 Sep 06:32:51 AM www.google.co.uk -- cern lhc recreate big bang black hole
9 Sep 06:26:59 AM www.google.co.uk -- lhc black hole wednesday
9 Sep 06:23:30 AM www.google.com -- black hole lhc
9 Sep 06:22:59 AM www.google.fr -- hawaii lhc black hole
9 Sep 06:22:51 AM www.google.ro -- lhc black hole
9 Sep 06:23:30 AM www.google.com -- black hole lhc
9 Sep 06:22:59 AM www.google.fr -- hawaii lhc black hole
9 Sep 06:22:51 AM www.google.ro -- lhc black hole
9 Sep 06:21:24 AM www.google.co.uk -- lhc black holes
9 Sep 06:20:01 AM www.google.bg -- happened create black hole
9 Sep 06:18:11 AM www.google.co.in -- is cern experiment leads to tsunami
9 Sep 06:18:05 AM www.google.com -- lhc black hole
9 Sep 06:17:40 AM www.google.com -- safety problems of cern
9 Sep 06:16:06 AM www.google.com -- what will happen lhc
9 Sep 06:15:53 AM www.google.co.uk -- cern safety
9 Sep 06:15:16 AM www.google.co.uk -- lhc risks site:blogspot.com
9 Sep 06:12:39 AM www.google.fr -- lhc black holes
9 Sep 06:12:37 AM search.yahoo.com -- lhc black hole
9 Sep 06:12:31 AM www.google.co.in -- how can lhc create big bang conditions
9 Sep 06:11:23 AM www.google.com -- lhc black hole

And so on and so forth. I've all said it repeatedly, but here is a summary for those of you with the really short attention span:

1. The LHC will not recreate the Big Bang. I repeat, the LHC will not recreate the Big Bang. No matter what you have read elsewhere. This statement is not only slightly inaccurate, it is simply plainly wrong by at least 19 orders of magnitude. For more details, please read Recreating the Big Bang?

2. The world will not end tomorrow. To produce a black hole at the LHC the world would need to have additional compactified dimensions, a so far completely unconfirmed speculation. Even in the unlikely event this would be the case, these black holes would decay almost immediately, long before they even reached the detector. There is no controversy about this in the community, no matter what you have read elsewhere. We do not know of any consistent theory according to which these black holes, once produced, would pose a risk. For more information, please read our posts The CERN Safety report, Black Holes at the LHC - again, Black Holes at the LHC - what can happen? and Micro Black Holes.

Please do me the favour and do not ask questions without having read the above mentioned posts, because I am really tired of repeating the same points over and over again. It is really not that hard to understand, just give it a try.

It is quite ironic that I spoke about these two examples in my talk yesterday to explain how difficult communication between scientists and the public can be.

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## Monday, September 08, 2008

### Science is a Worldview

I've been up half of last night preparing the talk for this morning. Certainly not something I like to do, but trying to express why I organized this conference has been very useful to structure my thoughts. I eventually condensed it down into one sentence “Science, Information and Knowledge needs Management,” and I hope I got this message across. Well. Given that I repeated it three times, you'd have to be blind and deaf not to have gotten it.

This first day has been going very well (except for the need to re-re-revise the schedule). Three people already asked me whether this would become an annual event! I am certainly in favor in it. I think the management of information - and scientific information specifically - will become an increasingly important topic, for the internal organization of sciences as well as for its embedding into the society we are part of. It is a topic that draws on input from the natural sciences, the social sciences as well as the computer science, and is as such an interdisciplinary endeavor that needs a forum to focus insights and put them into good use.

While organizing this meeting, I've been wondering whether it will work out combining people from the social sciences with the natural sciences, but so far it makes for a very inspiring mix. We will see how it goes the rest of the week. Wednesday is 'social science' day, as you can see if you look at the schedule. Katy Börner's poster exhibition arrived well and is displayed in the atrium. She will talk about the visualization of community structures and the Maps of Science tomorrow afternoon.
“Science is as old as mankind. We observe nature, we try to understand its working, both to make our lives more pleasant and to find our place in this universe – both, for the sake of application, and because we want to understand who we are, what we are made of and where we come from.

The most important difference between human beings and other species is our ability to pass on knowledge – over increasingly long distances in space and in time. And during our evolution, this allowed scientific research to grow to an organized endeavor, managing an increasing body of knowledge.

Today, science is a community enterprise. It provides us with insights that allow us to shape our future, and to drive progress.

I went into science because I wanted to contribute part, if only a small part, to this body of knowledge. And recently I’ve become interested in the management of that knowledge itself.”

Those were my opening words. The recording is already online at PIRSA, and my slides are here (it's a 5 MB powerpoint presentation).

Chad Orzel from Uncertain Principles then continued with a very well done talk later this morning (recording here) in which he stressed the importance of scientific research to be communicated in a more accessible way. I particularly liked his points "What to do" (around min 31)- I always like concrete suggestions for improvement.

In the afternoon we had Jacques Distler who explained the advantages of MathML, and the usefulness of blogs and wikis which has certainly been an interesting talk for many people in the audience - though I admit it doesn't really fall into my own area of interest. If you want to know more, check the recording. The last talk today was by John Willinsky, who impressed everybody by talking without any powerpoint slides whatsover (recording here). His talk was a plea for open access, summarizing with many examples the positive effects that opening up access to scientific publications has already had.

Later in the afternoon we had a panel discussion with Chad, John, and Cameron, lead by Eva Amsen. Eva did a great job, and we covered various issues of science getting closer to the public: the role of blogs, problems with science education, open access textbooks, free availability of data, and a lot more. I encourage you to look at the FriendFeed where Michael created a room for the conference. I myself am new at FriendFeed but it is really simple to use, and provides you with a good sense of what is going on.

In the evening then we had Alex Pang from the Institute for the Future doing a roadmap of the future of science. We were all supposed to write on post-its what we think will become important in the future, which was then arranged on a black board. It will be up there for the next couple of days, and since it is in the PI bistro, it is likely that some PI residents will contribute to it. I will make sure that I take a picture and upload it. Many of the points were very interesting.

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### CERNism

With the startup of the LHC coming closer, here are some CERNisms

And while everything is ready to go in Geneva, scientists in the USA receive death threats...

## Sunday, September 07, 2008

### Interna II

While my wife is busy with all kinds of last-minute preparations for the conference tomorrow, I've spent the weekend unpacking the last bunch of boxes. Normal life hopefully will resume soon, including an occasional contribution to our blog...

In the meantime, just days before the first beam is supposed to go around in the LHC, I've come across a portrait of physicist Peter Higgs very worth reading in this week's edition of the German newspaper Die Zeit, "Das Teilchen Higgs".

As most of you don't read German, never mind, it's Higgs time in British newspapers anyway: I can refer you instead to the portraits Father of the 'God Particle' by James Randerson in The Guardian of June 30, 2008 , Prof Peter Higgs interview: Smashing atoms at CERN and the hunt for the 'God' particle by Roger Highfield in the Telegraph of August 4, 2008, or The man with the answer to life, the universe and (nearly) everything by Jonathan Leake from The Sunday Times of August 17, 2008.

For a bit more technical background on the prehistory of the "Higgs boson", and the role of many other physicists played in it, check out Peter Higgs: the man behind the boson by Peter Rodgers in Physics World from July 10, 2004, which includes links to all the relevant original papers, or listen to Peter Higgs himself telling the story of My Life as a Boson (recorded on May 21, 2001 at the Michigan Center for Theoretical Physics).

And, of course, Peter Higgs is also on YouTube.

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## Saturday, September 06, 2008

### Interna

Sorry for the silence folks, two days before our conference starts my inbox is about to collapse into a black hole. Can you believe I've spend a whole day doing nothing than replying to and forwarding emails? I now know how it feels like being a node in a network. Meanwhile, I am still preparing my recently acquired talk on Monday morning. I am trying to mention all other talks along the way. Somewhat like one of these games where you have to write a story including the following five words: Beer, Footprint, Credit Card, Collision, Deoxyribonucleic acid. There's always one that doesn't fit in.

Something completely different: I recently came across this LHC rap. Not quite my kind of music, but entertaining nevertheless.

## Thursday, September 04, 2008

### Brian Greene's public lecture

Yesterday evening I went to Brian Greene's PI public lecture "Black Holes and a Myth of Icarus". The lecture was sold out, the place was crammed and suffered from a severe lack of oxygen. I just love going to the public lectures. It's such a nice experience to see how much interest there is in our work. Not to mention going straight to the first row and sitting down on a seat with a sign 'Reserved'.

Brian started with a quite bizarre story of how he just accidentally mistook the shower gel for mouth wash. Seemed to me like the kind of warm-up joke you learn in a seminar. Anyway, the lecture considerably improved after that. Brian spoke about his latest book "Icarus at the Edge of Time" that was just published this week. It is a fiction story about a teenager on a spaceship who is intrigued by a black hole in the vicinity of the spaceship's path. In the story of that boy there is embedded quite a bit of black hole physics.

He also said that the reason for him writing a fiction book is that science sadly too often is communicated in a rather boring way, and not as the exciting story of discovery that it really is. He later also added that the educational system brings kids up to the scientific status of 1688, but leaves out most of modern science. I'm not entirely sure what he was referring to there, I roughly agree on the sense but at least we learned Special Relativity and some basics of quantum mechanics in high school.

As far as I am concerned, embedding science into stories has always annoyed me. I'd have appreciated less clutter and a more precise formulation in class as well as in textbooks (see also the discussion of my post Text + Equations = Clarity?). I found it quite interesting to read about recent research results that show real world examples are not particularly helpful to illustrate mathematical concepts. Indeed, the task to translate "word problems" into equations is most often the hardest part - still in my research today.

Anyway, I am sure the audience liked Brian Greene's performance. And no, I won't buy the book.

## Tuesday, September 02, 2008

### Turtles all the way up

I got up this morning particularly early to hear Paul Davies' talk at the Multiverse conference currently taking place at PI. Just to find out upon arrival that his talk had been moved to an even earlier time and I missed it. So, now I'm catching up by watching the recorded lecture (see PIRSA 08090042).

Paul Davies is an excellent speaker. I thought he would have made a good wake-up talk, now he's talking to me to sleep. I am equally impressed as depressed that one could take a transcript of his talk and just publish it - no *oohms*, no *aahs* no inflation of Okay's, Right's or other glitches. That's depressing because my stuttering will likely never get anywhere close to that.

Either way, Paul started his talk with the question of whether in our search for fundamental laws we might always find an even more fundamental theory - nicely summarized in the explanation that our world rests on the back of an elephant, who stands on the back of a turtle, and if you wonder what the turtle is standing on - well, it's turtles all the way down. (See Wikipedia for full story.) Translate into: if we look closer into the microscopic features of nature, we might have to refine our theories over and over again.

Alternatively, there might be a fundamental theory, a final "Superturtle", so Paul suggests, to hold the tower of turtles. It seems to me quite a substantial fraction of theoretical physicists today believes in the existence of the Superturtle. Though one might ask whether it is even possible for us to decide between turtles all the way down and the final Superturtle, given that we lack experimental evidence for even the next turtle. See also my earlier post Will Physics turn into Philosophy?

Last week, I attended a conference on Emergent Gravity. The idea behind these approaches is roughly that the laws of nature we currently use and the ingredients of our present theories, including space and time itself, are not fundamental, but "emerge" from a potentially completely different microscopic description.

The following four pictures might give you a very sketchy analogy of emergence. Depending on the level you "zoom" in you will be able to recognize different patterns, and you might chose different ways to describe what you see. Similarly in nature, depending on the level we "zoom" in, different variables might be useful to describe what we see. (If you get lost in the multiphoto, the zoom is onto the upper right corner.)

The phenomenon that a different resolution of structures makes other variables more appropriate is familiar from an abundance of examples. You wouldn't describe cells with the standard model or particle physics - not because it doesn't apply, but because that description would be essentially useless and utterly inappropriate. The cell is better characterized by other variables, as might be the in- and output of certain chemicals. Likewise, it isn't of much use to describe human behavior by considering all cells humans are made of. Effective theories in physics are an especially strict notion of making sense of resolving structures only to a limited precision, in which case the ingredients of your theory might change. (See also my post on Emergence and Reductionism.)

Anyway, given the nature of this conference on the Multiverse, I think the question to ask here is instead whether it's turtles all the way up? If we consider the universe at larger and larger scales - possibly beyond what we can observe, would there be emergent laws connecting these universes? Emerging Multiverse-superlaws determining how we are embedded in the ensemble of universes that we might be part of? And is is possible for us at all to say something about these turtles?

(Aside: Min 37 - James Hartle's commentary on Max Tegmark's Mathematical Universe. He is criticising Max' use of the word 'exist'. I totally agree with Jim, that's exactly my criticism, see my post on The Mathematical Universe.)

### Science 2.0

Robin Lloyd from LiveScience wrote a nice article about how the internet has in many ways resulted in less secrecy and more openness in science

I recommend reading the article, if only because I'm quoted in several places :-)