Saturday, December 31, 2011

Happy New Year!

We wish all our readers a good start into the year 2012! We hope that you find the insight you have been looking for, get the job you want or the grant you need. May it be a delightful year for you.

I'll use the opportunity to dump a few interesting links I've come across lately:

Thursday, December 29, 2011

Happy Birthday, Lara and Gloria

Today, Lara and Gloria are one year old!

In this year, they have more than tripled their birth weight and they have grown more than 50%. In terms of growth, Lara is still ahead of her sister, meanwhile 2cm taller and 2 pounds heavier. In an amazing demonstration of neural network growth, the girls have learned to smile, to laugh, to hold their head, to turn around, to grab and to pick up crumbles. They have learned to eat from a spoon, to crawl, to sit up, and to stand. They have been through all vowels and are currently working their way through the consonants. They like to take and give toys, and as of lately have learned to throw them. They have both made the first stumbling step, but still deem crawling safer.

Lara has meanwhile two teeth and has found out that grinding them makes her daddy draw funny faces. Gloria has one tooth and now discovers all the possible ways to make noise with it, like running it up and down the bed posts or biting on cups.

It is interesting that while the girls are very different in character, they have made all developmental steps almost simultaneously. If one of them learned something new, the other would soon follow. The one exception is that before Lara could crawl, she had a phase of moving by rolling sideward that Gloria entirely skipped.

Every month, somebody told us the worst is yet to come. The worst are the first three months because they don't sleep through the night. The worst are months four to six because they sleep less during the day but can't yet use any toys, so want to be entertained around the clock. But wait, the worst are months six to nine because they get mobile and you can no longer just put them somewhere and go about your own business. Months nine to twelve are the worst because they get teeth and there goes your night rest. Now that the first year comes to an end, we've been told 12 to 18 months are the worst, because they start to walk and you can't leave them alone for a second. And just wait till they start talking!

As for me, the worst were month -3 to 0, everything after delivery was a vast improvement; I clearly wasn't constructed to carry around 17kg excess weight.

Still, this year has been very exhausting to say the least. We changed an estimated 5000 diapers, picked up pacifiers 20000 times, and our commuting from Heidelberg to Stockholm and my occasional conference attendance has been organizationally challenging. Scientifically, it went better than expected, in that I did manage to write two proposals (one of which was meanwhile declined however), gave a few talks, am organizing a workshop, and did indeed publish a paper. For me, the main problem working from home is the difficulty staying in touch with colleagues, which is also why there are some papers in the pipe that are not making much progress.

Stefan and I, we have been fighting now for more than a year with various institutions in Germany and Sweden for our parental benefits. Just in time for Christmas, we received good news: three quarters of what Stefan applied for has been approved. The problem with the remaining quarter is a fundamental incompatibility between counting in German and Swedish. The Germans count the months of parental benefits starting with the day the child is born (i.e. the 29th in our case); the Swedes count from the 21st on. In addition, the Germans count a month of leave as "taken" even if only one day has been taken. Based on this, they have calculated that for us the year 2011 has 13 months, and we've applied for one month in excess since we mistakenly assumed the year has 12 months.

We still haven't seen a single cent child allowance.

We have also encountered an ambitious local photographer, who has plastered the town with advertisements for "baby-shooting," and whom you have to thank for the creative arrangement in the below photo.

PS: You find some little videos here.

PPS: For birthday greetings more material than words, on Lara and Gloria's Amazon wishlist you can find what the girls will need in the coming months.

Monday, December 26, 2011

The fifth candle: Advent calendar encore

While I was looking for fodder for the advent calendar, I came across this story in "A Passion for Discovery," by Peter Freund. Freund, a professor emeritus for theoretical physics, recalls anecdotes that he has witnessed or has been told throughout his career, such as this one:
Cranks approach scientists more often than you would guess. The main strategy for dealing with them is never to get into an argument, for they will not spare any of your time to convince you that they are right. The other useful trick is to convince the crank that you do not have the required expertise to be initiated in their sacred truth.

Another strategy: Academician N.N. Bogoliubov at Moscow State University was once approached by a crank. "I unfortunately am not qualified to discuss your work" Bogoliubov told the man, "but Academician Lev Landau is working on related problems. He is the man you are looking for." [...]

On another occasion... two men from the Shah of Iran's Vienna Embassy showed up [at the Institute for Theoretical physics in Vienna where the author was located at that time]. One of the two Iranians excitedly told us about their discovery, while his companion nodded along. They had apparently discovered that time does not exist. Their proof was eminently simple. "By the time I say now, now is already over. Quot Erat Demonstrandum." Did we not agree that this was a major discovery, and what should they do with it? Armed with our two principles, we agreed that the discovery was major and suggested they work out all its implications, especially practical applications, for they would likely make a great deal of money. This did the trick; the two left happy men.

Sunday, December 25, 2011

Merry Christmas

We wish all our readers a merry Christmas! And if you're not into heathen traditions turned Christian turned capitalist, we wish you a peaceful and happy day anyway :o) As promised, we conclude our advent calendar with a quiz:
  1. Erwin Schrödinger had a daughter with the wife of which physicist colleague? (First and last name, 11 letters.)

  2. The catholic church of which town has windows that were designed by an artist with education in physics who used pictures of three-jet events, spectroheligrams and Feynman diagrams? (6 letters)

  3. Which physicist introduced constants of length, mass and time with the motivation that they would be meaningful also for extraterrestrials? (Last of his middle names, 6 letters).

  4. According to a study published in the Journal "Sex Roles" in 1979, at which age in months are human female infants the cutest? (Write down English word for the number.)

  5. Which chemical element forms together with chloride a solid that at room temperature is blue in its pure form but turns purple when it binds (pure) water? (6 letters)

  6. Approximately at which volume, in liters, does an (average) human stomach burst, according to a study performed on organs of deceased, published in Revue médicale de la Suisse romande, in 1885? (One digit).

If you write down the answers in the order of the questions you should get a string with 34 symbols. The following entries give you the solution to this year's quiz: 33-11-1-24-15-34-17-27-31-20-22-26-23.

This year's prize is a BackRe(Action) mug and it will go to the first who submits the right answer in the comments. (For the shipment, we'll need your snail-mail address. If you are not willing to provide your address, please do not spoil the fun.)

Hint: The answers to question 1,3,4 and 6 can be found on this blog. The answers to question 2 and 5 can be found on Wikipedia. If I notice you're stuck, I will provide more hints in the comments.

Saturday, December 24, 2011

Advent calendar #24: Bohr's theory of the Wild West

Today's anecdote about Niels Bohr comes from George Gamow's book "Thirty years that shook physics - The story of quantum theory." This is the same Gamow we have met earlier in correspondence with Wolfgang Pauli. Gamow is the person who famously predicted the cosmic background radiation long before it was discovered. In the late 1920s, he was a student in Copenhagen under Niels Bohr, and tells the following:
The only movies [Bohr] liked were Wild Westerns (Hollywood style), and he always needed a couple of his students to go with him and explain the complicated plots... But his theoretical mind showed even in this movie expeditions. He developed a theory to explain why although the villain always draws first, the hero is faster and manages to kill him. This Bohr theory was based on psychology. Since the hero never shots first, the villain has to decide when to draw, which impedes his action. The hero on the other hand acts according to conditioned reflexes and grabs the gun automatically as soon as he sees the villain's hand move. We disagreed with this theory, and the next day I went to a toy store and bought two guns in Western holders. We shot it out with Bohr, he being the hero, and he "killed" all his students.

Friday, December 23, 2011

Advent calendar #23: Moonshine in Rutherford's brain

Ernest Rutherford is known for his achievements in atomic and nuclear physics, most essentially the insight that the mass of the atom is concentrated in a small nucleus. This is known today as the Rutherford model of the atom, and was experimentally shown by scattering alpha particles on gold. Rutherford won the Nobel prize for Chemistry in 1908 for his investigations into the disintegration of the elements, and the chemistry of radioactive substances.

In 1933, he gave a talk at a meeting of the British Association for the Advancement of Science, from which he was quoted in The London Times of September 12, 1933 about the possibility of energy-efficient nuclear fission as follows:

We might in these processes obtain very much more energy than the proton supplied, but on the average we could not expect to obtain energy in this way. It was a very poor and inefficient way of producing energy, and anyone who looked for a source of power in the transformation of the atoms was talking moonshine. But the subject was scientifically interesting because it gave insight into the atoms.

The 16 September 1933 issue of Nature tells its readers about the talk:

One timely word of warning was issued to those who look for sources of power in atomic transmutations ‒ such expecations are the merest moonshine.

It is easy to invoke this statement as a further example for a severe scientific misjudgement by a senior scientist. But in context, it was perfectly reasonable: Rutherford was discussing nuclear reactions tiggered by the proton beam from the then brand-new accelerator of Cockroft and Walton. Trying to gain nuclear energy that way is about as efficient as producing antimatter at CERN to fuel a matter-antimatter-annihilation engine.

Moreover, in his paper Atomic Energy is "Moonshine": What did Rutherford Really Mean?, historian of science John G. Jenkin argues that Rutherford was well aware that there might be ways to harness nuclear energy, especially using neutrons as tools to induce reactions. He suggests that Rutherford "in all of his later negative pronouncements regarding the possibility of atomic energy, was adopting a quite deliberate policy to disguise and postpone, for as long as possible, the awful prospect that he saw looming over the horizon: a new and dreadful war, a new and devastating weapon, and unprecedented destruction."

On a lighter side, Rutherford also allegedly warned (quoted for example in "The Strangest Man: The hidden life of Paul Dirac" by Graham Farmelo):
"Don't let me catch anyone talking about the universe in my department!"

and said about special relativity (quoted for example in "The Nobel Prize: A History of Genius, Controversy, and Prestige" by Burton Feldman):
"Oh, that stuff. We never bother with that in our work."

Though I am not sure about the origin of this latter quotation.

Rutherford was reportedly skeptic about special relativity in its early days, and for most of atomic physics it can be safely neglected and one does indeed not have to bother. But when in 1930 he prepared a new and updated edition of his book "Radiation from Radioactive Substances", he did add a discussion of the mass defect based on E = mc².

Thursday, December 22, 2011

Advent calendar #22: Space, Time and Birds

Today's anecdote about Werner Heisenberg has been preserved by Felix Bloch in his article "Heisenberg and the early days of quantum mechanics" Physics Today, December 1976:
We [Werner Heisenberg and Felix Bloch] were on a walk and somehow began to talk about space. I had just read Weyl's book Space, Time and Matter, and under its influence was proud to declare that space was simply the field of linear operations.

"Nonsense," said Heisenberg, "space is blue and birds fly through it."

This may sound naive, but I knew him well enough by that time to fully understand the rebuke. What he meant was that it was dangerous for a physicist to describe Nature in terms of idealized abstractions too far removed from the evidence of actual observation. In fact, it was just by avoiding this danger in the previous description of atomic phenomena that he was able to arrive at his great creation of quantum mechanics. In celebrating the fiftieth anniversary of this achievement, we are vastly indebted to the men who brought it about: not only for having provided us with a most powerful tool but also, and even more significant, for a deeper insight into our conception of reality.

Wednesday, December 21, 2011

Advent calendar #21: Bohr and the horseshoe

The web is full with anecdotes and quotations about physicists and mathematicians. It would not be difficult to fill a whole year with stories Google put at my fingertips, but then I could as well make them up myself. The time-intensive part of this advent calendar has not been to find the stories but to find out if they have a reliable source. Inevitably, some widely spread stories, if they had any source at all, turned out to have been altered several times, much like a digital game of Chinese whispers.

One such story is for example that of Niels Bohr and the horseshoe. The version on this website goes like this:
"An American scientist once visited the offices of the great Nobel prize winning physicist, Niels Bohr, in Copenhagen. He was amazed to find that over Bohr's desk was a horseshoe, securely nailed to the wall, with the open end up in the approved manner (so it would catch the good luck and not let it spill out). The American said with a nervous laugh,

"Surely you don't believe the horseshoe will bring you good luck, do you, Professor Bohr? After all, as a scientist --" Bohr chuckled.

"I believe no such thing, my good friend. Not at all. I am scarcely likely to believe in such foolish nonsense. However, I am told that a horseshoe will bring you good luck whether you believe in it or not."

In some other versions that you can find online it's a student who asks the question, in yet some other versions the horseshoe is not above the desk but above the door to Bohr's cottage. The above version is particularly interesting for the amount of irrelevant details that somebody or maybe several people have added. Wikipedia lists the quote as disputed.

To find the origin of that story it is useful if you speak German, since it goes back to Werner Heisenberg's book "Der Teil und das Ganze" (The part and the whole). Most of the book is a recollection of conversations Heisenberg had with Niels Bohr and Wolfgang Pauli, among others. Heisenberg wrote down these conversations long after they had taken place, so one should not expect the exchange to have been word by word exactly as he reported. Heisenberg finishes Chapter 8 on "Atomphysik und pragmatische Denkweise" (atomic physics and pragmatism) with an anecdote that Niels Bohr told:
Niels schloß das Gespräch ab mit einer jener Geschichten, die er bei solchen Gelegenheiten gern erzählte: "In der Nähe unseres Ferienhauses in Tisvilde wohnt ein Mann, der hat über der Eingangstür seines Hauses ein Hufeisen angebracht, das nach einem alten Volksglauben Glück bringen soll. Als ein Bekannter ihn fragte: "Aber bist du denn so abergläubisch? Glaubst du wirklich, dass das Hufeisen dir Glück bringt?", antwortete er: "Natürlich nicht; aber man sagt doch, daß es auch dann hilft, wenn man nicht daran glaubt.""

Niels finished with one of these stories he liked to tell on such occasions: "Near by our vacation house in Tisvilde lives a man who has a horseshoe above his door, after the old superstition that it brings luck. When a friend asked him "Are you superstitious? Do you really believe the horseshoe brings luck?" He replied "Of course not; but they say it also helps if you don't believe it."
~Werner Heisenberg, Der Teil und das Ganze, 1973, p. 112/13

So if you plan on winning a Nobel prize, be careful with the anecdotes you tell. Later generations might unashamedly turn the narrator into a subject and the details may be buried in translation.

Tuesday, December 20, 2011

Advent Calendar #20: Fermi's driver

Enrico Fermi had quite a dry sense of humor. George Gamow, in his book Thirty Years that Shook Physics: The Story of Quantum Theory, relates the following story from the time when Fermi was a professor in Rome in the 1930s:
Once Fermi had to attend a meeting of the Academy of Sciences at the Palazzo di Venezia, which was strongly guarded because Mussolini himself was to address it. All other members arrived in large foreign-made limousines driven by uniformed chauffers, while Fermi drew up in his little Fiat. At the gate of the Palazzo he was stopped by two carabinieri who crossed their weapons in front of his little car and asked his business there. According to the story he told to the author of this book, he hesitated to say to the guards: "I am His Excellency Enrico Fermi," for fear that they would not believe him. Thus, to avoid embarrassment, he said: "I am the driver of His Excellency, Signore Enrico Fermi." "Ebbene," said the guards, "drive in, park, and wait for your master."

Upcoming Christmas Quiz

In good tradition, we'll finish our seasonal program with a quiz, which is prescheduled for December 25th, 4pm Central European Time, that's 10am on the East Coast. This year's prize is a BackRe(action) mug (see photo), though of course it's more about the fun than about the prize.

Every year I put together the questions and use Stefan as a guinea pig. If he manages to solve the quiz in less than 10 minutes it's too easy. If he hasn't worked it out in 2 hours, taking into account that he knows fairly well the likely sources I have used, it's too difficult. On the Stefan-scale, this year's quiz is more difficult than the ones before, so don't miss it!

The quizzes from the previous years are here: 2007, 2008, 2009, 2010.

Monday, December 19, 2011

Advent Calendar #19: Confident Einstein

In September 1919, Ilse Schneider was working on her Ph.D. thesis in philosophy at the university of Berlin on the "space-time problem in Kant and Einstein". She did profit from the fact that the creator of the theory of relativity was a professor in the physics department: She attended Einstein's lectures, and met regulary with him to discuss the meaning and implications of his theory.

At that time, Einstein was eagerly waiting for news about the results of the British eclipse expedition by Eddington, who had tried to measure the deflection of light by the sun as predicted by the general theory of relativity. Einstein's theory of general relativity is a remarkable achievement of a brilliant mind that knew how to make use of mathematics. Einstein had to try around somewhat before he found the correct equations, but once he had arrived there, he had little doubt they did describe nature correctly.

In her memoir "Reality and Scientific Truth: Discussions with Einstein, von Laue, and Planck", Ilse Rosenthal-Schneider remembers on of her meetings with Einstein from that time:

Suddenly Einstein interrupted the reading and handed me a cable that he took from the window-sill with the words, "This may interest you." It was Eddington's cable with the results of the famous eclipse expedition. Full of enthusiasm, I exclaimed, "How wonderful! This is almost the value you calculated!" Quite unperturbed, he remarked, "I knew that the theory is correct. Did you doubt it?" I answered, "No, of course not. But what would you have said if there had been no confirmation like this?" He replied, "Da könnt' mir halt der liebe Gott leid tun. Die Theorie stimmt doch." ("I would have had to pity our dear God. The theory is correct anyway.")

We thank Toby Bryant for reminding us of that story! According to the Einstein biography by Albrecht Fölsing, Einstein did receive a telegram from Lorentz in Leiden on September 22, 1919, reporting preliminary results on the light deflection as compatible with the prediction of general relativity.

Sunday, December 18, 2011

Advent calendar #18: Heisenberg and the microscope

Werner Heisenberg is well known for his analysis of the inevitable uncertainty in observations with a microscope that eventually lead him to formulate the uncertainty principle. Less known is the origin of his obsession with microscopes. In 1923, Heisenberg was heading towards the final oral examination for his doctorate. He passed mathematics, theoretical physics and astronomy just fine, but he run into troubles with experimental physics where he was to be examined by Wilhelm Wien.

Wien had required that Heisenberg did a "Praktikum" (basically a practice in physics experiments), but there was some equipment lacking and Heisenberg wasn't interested enough to find out where to get it. He thus turned towards other things without looking much into the experiments he was supposed to do, for example measuring the splitting of spectral lines by help of an interferometer. Then came the day of the oral exam:
"Wien was annoyed when he learned in the examination that Heisenberg had done so little in the experimental exercise given to him. He than began to ask him questions to gauge his familiarity with the experimental setup; for instance, he wanted to know what the resolving power of the Fabry-Perot interferometer was... Wien had expained all this in one of his lectures on optics; besides, Heisenberg was supposed to study it anyway... But he had not done so and now tried to figure it out unsuccessfully in the short time available during the examination. Wien... asked about the resolving power of a microscope; Heisenberg did not know that either. Wien questioned him about the resolving power of telecopes, which [Heisenberg] also did not know."

(From Jagdish Mehra, Helmut Rechenberg: "The Historical Development of Quantum Theory Vol. 2 - The Discovery of Quantum Mechanics 1925" p. 67)

Wien wanted to fail Heisenberg, but Sommerfeld, in whose exam on theoretical physics Heisenberg had excelled, put in a strong word for Heisenberg. Heisenberg passed the doctoral examination with the lowest possible grade. Many years later Heisenberg would recall
"So one might even assume, that in the work on the gamma-ray microscope and the uncertainty relation I used the knowledge which I had acquired by this poor examination."

Saturday, December 17, 2011

Advent Calendar #17: Fermi's paper snippets

Enrico Fermi is famous for his ingenious ways to arrive at quantitive estimates for the solution of complicated physical problems. One of the most legendary examples is his estimate of the energy released by the first atomic bomb. As Fermi himself recalls in My Observations During the Explosion at Trinity on July 16, 194,

About 40 seconds after the explosion the air blast reached me. I tried to estimate its strength by dropping from about six feet small pieces of paper before, during, and after the passage of the blast wave. Since, at the time, there was no wind I could observe very distinctly and actually measure the displacement of the pieces of paper that were in the process of falling while the blast was passing. The shift was about 2 1/2 meters, which, at the time, I estimated to correspond to the blast that would be produced by ten thousand tons of T.N.T.

Emilio Segrè, who witnessed the event together with Fermi, gives a few more details. In his biography Enrico Fermi, Physicist, he writes that Fermi had done the necessary calculations in advance, "having prepared himself a table of numbers, so that he could tell immediately the energy liberated from this crude but simple measurement."

At Los Alamos, Enrico Fermi had the role of an "oracle": Because of his enormous knowledge and competence in all areas of physics, he was consulted for all kinds of physical problems. However, his mastery of physics could be intimidating to other physicists.

As a bonus, here is a story remembered by Subrahmanyan Chandrasekhar, who was a colleague of Fermi at the University of Chicago in the early 1950s (Bull. Amer. Math. Soc. Vol. 84, No. 3 (1978), p. 431):

Some twenty-five years ago, I met a colleague of mine emerging from the office of Enrico Fermi. He told me that he had been discussing physics with Fermi; and after a moment's pause asked, "Why am I doing physics? I should probably be a grocer".

Friday, December 16, 2011

Advent calendar #16: Stern's cigar

This is a story one cannot escape if one studies physics in Frankfurt am Main.

In 1922 Otto Stern and Walther Gerlach demonstrated the directional quantization of angular momentum by sending silver atoms through an inhomogeneous magnetic field. Silver has only one electron in the valence shell, so the orbital angular momentum vanishes and only the electron spin contributes to the total angular momentum of the atom. Depending on the orientation of the spin relative to the magnetic field, the atom takes one out of two trajectories, leading to a discrete splitting of the beam after it passed the magnetic field. Classically, one would expect a smooth distribution. This experiment, conducted in Frankfurt am Main, is known today as the Stern-Gerlach experiment, and was one of the milestones on the way to quantum mechanics.

But it was not just the ingenuity of the experimenters that lead to success since originally Stern and Gerlach couldn't see anything on the screen that should be showing two discrete lines. Dudley Herschbach, who won the Nobel prize for Chemistry in 1986, retold Stern's description of the discovery as follows:

"After venting to release the vacuum, Gerlach removed the detector flange. But he could see no trace of the silver atom beam and handed the flange to me [Stern]. With Gerlach looking over my shoulder as I peered closely at the plate, we were surprised to see gradually emerge the trace of the beam... Finally we realized what [had happened]. I was then the equivalent of an assistant professor. My salary was too low to afford good cigars, so I smoked bad cigars. These had a lot of sulfur in them, so my breath on the plate turned the silver into silver sulfide, which is jet black, so easily visible. It was like developing a photographic film."

The complete story of Stern and Gerlach's experiment can be found in Physics Today 56 (December 2003) Stern and Gerlach: How a Bad Cigar Helped Reorient Atomic Physics (pdf), by Bretislav Friedrich and Dudley Herschbach. They also went on to test the plausibility of this story and repeated the original experiment at its 80st anniversary. The found that bad breath alone wouldn't do the trick, but that more likely Stern was actually puffing on a cigar when Gerlach handed him the invisible result.

Thursday, December 15, 2011

Advent calendar #15: The end is nigh

In 1903, briefly before the dawn of Special Relativity and Quantum Mechanics, Albert Abraham Michelson offered his view on physics:
“The more important fundamental laws and facts of physical science have all been discovered, and these are so firmly established that the possibility of their ever being supplanted in consequence of new discoveries is exceedingly remote.”

~A.A. Michelson, Light waves and their uses, University of Chicago Press (1903)

Wednesday, December 14, 2011

Advent calendar #14: From Hilbert with Sympathy

Hilbert had a student who one day presented him with a paper purporting to prove the Riemann hypothesis. Hilbert studied the paper carefully and was really impressed by the depth of the argument; but unfortunately he found an error in it which even he could not eliminate. The following year the student died. Hilbert asked the grieving parents if he might be permitted to make a funeral oration. While the student's relatives and friends were weeping beside the grave in the rain, Hilbert came forward. He began by saying what a tragedy it was that such a gifted young man had died before he had an opportunity to show the world what he could accomplish. But, he continued, in spite of the fact that this young man's proof of the Riemann hypothesis contained an error, it was still possible that some day a proof of the famous problem would be obtained along the lines which the deceased had indicated. "In fact," he continued with enthusiasm, standing there in the rain by the dead student's grave, "let us consider a function of one complex variable..."

Quoted from "Hilbert" by Constance Reid, where it is noted that this story is "perhaps apocryphal."

Tuesday, December 13, 2011

Advent Calendar #13: A Postdoc's Nightmare

Pascual Jordan was, along with Werner Heisenberg, Paul Dirac, and Wolfgang Pauli, one of the Wunderkinder contributing to the development of quantum mechanics. He had obtained his Ph.D. in 1924, at the age of 22. In the following year, together with his Ph.D. advisor Max Born and with Heisenberg, he created the matrix formulation of quantum mechanics, formulating the canonical commutation relations between position and momentum. Jordan kicked off quantum field theory, and found the anti-commutation relation for creation and annihilation operators of particles with spin 1/2. These particles, now known as fermions, actually could be linked directly to Jordan, were it not for a case of extremely bad luck. As Max Born remembers:

In December of 1925 I went to America to give lectures at MIT. I was editor of the Zeitschrift für Physik, and Jordan gave me a paper to be published in the journal. I didn't find time to read it and put it in my suitcase. I forgot about it, and when I returned half a year later and unpacked, I found the paper at the bottom of the suitcase. It contained the Fermi-Dirac statistics. Meanwhile both Fermi and Dirac had discovered it. But Jordan was the first.

The Max Born quote, and more about Jordan, can be found in Engelbert Schuckings reminescences "Jordan, Pauli, Politics, Brecht... and a Variable Gravitational Constant" (in On Einstein's path: Essays in Honor of Engelbert Schucking).

Monday, December 12, 2011

Advent calendar #12: All of astronomy

In 1904, Max Born, a German born physicist who would win the Nobel prize in 1954, went to Göttingen to study mathematics and physics. He soon made friends with Professor Karl Schwarzschild, who taught astronomy, and at that time was not much older than his students. Schwarzschild's name might be familiar to you from the Schwarzschild-metric - the first known exact solution to Einstein's field equations that he would derive about a decade later.

In their book "Der Luxus des Gewissens" (The Luxury of Conscience) by Max Born and his wife Hedwig, Born recalls that he used to play tennis with Schwarzschild. Max Born (who was called "Maxel" by his friends) liked Schwarzschild's astronomy class, but did not feel very inspired by the lectures on geometry, held by the great mathematician Felix Klein, namegiver of the Klein bottle:
"Die geometrischen Vorlesungen... waren aber nicht nach meinem Geschmack, und ich besuchte sie nicht sehr regelmäßig... Mein Reinfall im müdlichen Examen, das in nur sechs Monaten bevorstand, schien unvermeidlich."

"The lectures in geometry... were not to my taste and I did not attend them on a regular basis. That I would flop at the oral exam, to which there were only six months to go, seemed unavoidable."

Maxel asked his friend Schwarzschild for advice. Schwarzschild suggested to instead take the exam in astronomy:
"[E]r sagte, ein halbes Jahr sei reichlich Zeit, die ganze Astronomie zu lernen."

"He said, half a year is more than enough time to learn all of astronomy."

Max passed the oral exam in astronomy, even though he answered the question "What do you do when you see a falling star?" with "I make a wish!" and only after Schwarzschild's further inquiry remembered to add "I note down the time and location, the direction and the length of the visible trace."

Sunday, December 11, 2011

Advent calendar #11: Prescient Einstein

From Bertram Kostant (Professor Emeritus of Mathematics at MIT) via Garrett Lisi @ Physics Forums comes the following anecdote:

"I was a visiting member of Princeton's Institute for Advanced Study in 1955. It was a Good Friday in April and Einstein was looking for the Institute bus to take him back home to 112 Mercer Street. Being Good Friday, the driver was on holiday amd I offered to drive him home. We had a wonderful conversation and at one point he asked me what I was working on. I told him Lie groups. He then remarked, wagging his finger, that that will be very important. Actually, I was quite surprised that he knew who Lie was. About a week later Einstein was dead."

Saturday, December 10, 2011

Advent calendar #10: It sounds Greek to me!

Of course we cannot allow Richard Feynman to be missing when we tell physics anecdotes. He told his anecdotes well himself, and they have been captured by Ralph Leighton in the book "Surely You're Joking, Mr. Feynman!" One of my favorites is this story:

I don't know why, but I'm always very careless, when I go on a trip, about the address or telephone number or anything of the people who invited me. I figure I'll be met, or somebody else will know where we're going; it'll get straightened out somehow.

One time, in 1957, I went to a gravity conference at the University of North Carolina. I was supposed to be an expert in a different field who looks at gravity. I landed at the airport a day late for the conference (I couldn't make it the first day), and I went out to where the taxis were. I said to the dispatcher, "I'd like to go to the University of North Carolina."

"Which do you mean," he said, "the State University of North Carolina at Raleigh, or the University of North Carolina at Chapel Hill?"

Needless to say, I hadn't the slightest idea. "Where are they?" I asked, figuring that one must be near the other.

"One's north of here, and the other is south of here, about the same distance."

I had nothing with me that showed which one it was, and there was nobody else going to the conference a day late like I was.

That gave me an idea. "Listen," I said to the dispatcher. "The main meeting began yesterday, so there were a whole lot of guys going to the meeting who must have come through here yesterday. Let me describe them to you: They would have their heads kind of in the air, and they would be talking to each other, not paying attention to where they were going, saying things to each other, like 'Gmunu.Gmunu.'"

His face lit up. "Ah, yes," he said. "You mean Chapel Hill!" He called the next taxi waiting in line. "Take this man to the university at Chapel Hill."

"Thank you," I said, and I went to the conference.

Friday, December 09, 2011

Advent calender #9: Prof. Jolly's advice

When Max Planck had finished high school in 1874, he was unsure which career path to chose. He had many different talents and interests, and pondered becoming a concert pianist, or study classical philology, or maybe mathematics and physics. Planck's father, a professor of law, mediated an appointment with his colleague, physicist Philipp von Jolly, for Max to get some advice. Prof. Jolly was a bit gloomy about the prospects of physics, and didn't want to raise false hopes in the young man. As Max Planck remembered,

Als ich meine physikalischen Studien begann und bei meinem ehrwürdigen Lehrer Philipp von Jolly wegen der Bedingungen und Aussichten meines Studiums mir Rat erholte, schilderte mir dieser die Physik als eine hochentwickelte, nahezu voll ausgereifte Wissenschaft, die nunmehr, nachdem ihr durch die Entdeckung des Prinzips der Erhaltung der Energie gewissermassen die Krone aufgesetzt sei, wohl bald ihre endgültige stabile Form angenommen haben würde. Wohl gäbe es vielleicht in einem oder dem anderen Winkel noch ein Stäubchen oder ein Bläschen zu prüfen und einzuordnen, aber das System als Ganzes stehe ziemlich gesichert da, und die theoretische Physik nähere sich merklich demjenigen Grade der Vollendung, wie ihn etwa die Geometrie schon seit Jahrhunderten besitze. (Max Planck, Wege zur physikalischen Erkenntnis, S. Hirzel, 1933, p. 128)

Philipp von Jolly described physics as a highly developed, almost fully matured science, which was about to reach a final form, now that the principle of conservation of energy had been discovered. He thought that there may be a speck or a vesicle left to be studied and classified in one or the other angle of the field, but that as a whole, the system had a fairly safe standing, and that theoretical physics was approaching the same degree of perfection reached by geometry already centuries ago.

Max Planck did not let himself be dissuaded from studying physics by this assessment, and the rest is history.

Thursday, December 08, 2011

Advent calendar #8: Einstein's old envelopes

When Herr Professor Doktor Einstein and his wife visited Mr and Mrs Hubble at Mt Wilson, at one stage the two ladies were left alone to swap confidences. Mrs Hubble pointed at the great telescope and explained that her husband used it “to study the nature of the universe” whereupon Frau Einstein retorted that “my husband does that on the back of an old envelope!”

Submitted by Cormac O' Raifeartaigh. This anecdote is mentioned for example in “The Day We Found the Universe” by Marcia Bartusiak.

Wednesday, December 07, 2011

Advent calendar #7: Bullshit with equations

“In [high energy] quantum physics, to observe something, you have to create it. Now this sounds scarily close to bullshit. But if it is bullshit, then at least it's bullshit with equations.”

~Frank Wilczek, public lecture at Perimeter Institute

(Recycled from November 2008)

Tuesday, December 06, 2011

Advent calendar #6: The dissolved Nobel Prizes

This is the most wondrous story in our advent calendar.

The two German physicists Max von Laue and James Franck won the Nobel Prize in 1914 and 1925 respectively. When the Nazis grew strong in Germany von Laue and Franck sent their medals, made of 23-karat gold, to Niels Bohr in Copenhagen. During these troublesome times many people were hiding or burying their family jewelry or anything of timeless value that they wanted to keep out of the Gestapo's hands, though it was illegal to send valuables out of country.

Unfortunately, by 1940 the Nazis made it to Copenhagen. Bohr was now in possession of two large gold pieces that carried von Laue's and Franck's names and clearly left Germany unapproved. Bohr had to get rid of the Nobel medals, and quickly so. It was Georgy de Hevesy, a colleague and friend from the department of chemistry, who came up with a ingeneous solution, quite literally: he would dissolve the medals.

Now gold is a precious metal and what makes it so precious is that it is slow to react with anything. It takes a mixture of acids known as aqua regia and time to dissolve gold, but at the end of a seemingly endless afternoon the medals were gone and left was a glass with a bright orange solution that didn't catch the interest of the Nazis.

But that wasn't the end of the story. After the war, de Hevesy returned to his lab and found the orange solution undisturbed in his shelf. He precipitated out the gold and sent it back to the Nobel Foundation in Stockholm. They recast the medals and gave them back to von Laue and Franck.

De Hevesy won the Nobel price for chemistry in 1943.

This story can be found in many books. It was recently told in some more details at NPR blogs: Dissolve my Nobel Prize! Fast!.

Monday, December 05, 2011

Advent calendar #5: Share the love

In 1933, Erwin Schrödinger moved to Oxford. The physicist Arthur March, best known for his (failed) attempt to give physical meaning to a Lorentz-invariant minimal length scale, was not only Schrödinger's colleague but also a close friend. Due to Schrödinger's initiative, March too got a position in Oxford. Summer 1933, on a vacation in Tyrol, Schrödinger went on a bike excursion with Arthur March's wife Hilde. Nine months later Hilde gave birth to Schrödinger's daughter. Arthur March did not seem to mind much, but Schrödinger's wife went on to have an affair with the mathematician Hermann Weyl, while Weyl's wife in return found comfort with the physicist Paul Scherrer.

This and other details of Schrödinger's illustrious life can be found in Walter Moore's biography Schrödinger: Life and Thought.

Sunday, December 04, 2011

Advent calendar #4: Einstein's haircut

In Stefan's bookshelf I found a little book "Einstein privat" by Friedrich Herneck who, on the book cover, is described as "one of today's leading Einstein researchers." Herneck interviewed Einstein's former household aid, Herta W., about everything from Einstein's smoking habits, over nicknames used in the family to how often Einstein fed the goldfish. Herta W. had the following to say about Einstein's haircut which, next to going sockless, has become trademark of the ingenious theoretical physicist:
"Wenn seine Haare zu lang waren, wenn es gar zu schlimm geworden war, dann hat [seine Frau Elsa] ihm das Haar mit der Schere abgeschnitten. Das hat er sich dann auch machen lassen. Da Frau Professor aber sehr kurzsichtig war und beim Haarschneiden ihre Lorgnette, ihre Stielbrille, nicht ständig benutzen konnte... Aber Herr Professor war eben nicht zu bewegen, zu einem Berufsfrisör zu gehen."

"When his hair grew too long, when it got really intolerable, then [his wife Elsa] cut his hair off with a scissor. He let her do that. But since Frau Professor was very shortsighted and, during cutting, could not always use her Lorgnette... But Herr Professor could not be bothered to see a professional barber."

"Frau Professor" is (here) the form of address for the professor's wife and a lorgnette are old-fahioned glasses that have to be held on a handle in front of one's eyes. Later in the interview there's more talk about Frau Professor's shortsightedness and it seems it was indeed serious. She was however too vain to permanently wear thick glasses.

Saturday, December 03, 2011


Lara and Gloria are now 11 months old. They can both stand, on wobbly knees, though most of the time they insist on holding onto the furniture. Lara has half of a first tooth and a second in the making, and Gloria's first tooth is just about visible. I of course have dutifully brushed Lara's halftooth with pink toothpaste, which she seems to find very amusing. The babies have both suffered through their first cold, luckily a mild version, and have learned to nibble on bread and cookies.

 It is interesting to see how different the girls are, even though they share not only the same parents, but also a room, clothes and toys. Lara is now a few centimeters taller and also an estimated two pounds heavier than Gloria. (We'll know more precisely at their next doctor's visit, which is in 2 weeks.) When Gloria falls, she inevitably starts crying dramatically until you pick her up. When Lara falls, she might make some surprised sound, though not always, and just move on. She does however occasionally start crying just because her sister cries. Gloria sucks her thumb (the left one), day and night; Lara never does. Lara does however gnaw on the bedposts with her half tooth.

 Trying to change Lara's cloths has become a fight because she kicks, throws towels and cloths around, and tries to grab everything close enough. If you pull her away or turn her back around, she laughs and tries even harder. Gloria is one charmingly smiling baby on the changing table, as long as she has her rubber ducky to suck on. But try to take the ducky away...

I meanwhile am fighting once again with the paperwork. Not only are my Swedish parental benefits running out on Tuesday, but the Germans are refusing to pay Stefan's parental benefits. After a lot of calls and letters, it turned out that they seem to have misread one of the Swedish documents I sent them and thought the amount I got for 5 months was for one month, then concluded we're too rich to apply for benefits in Germany. Now they want more paperwork, that I have to rout to Sweden and back. For that and some other reasons I am somewhat stressed out in these darkest weeks of the year, so excuse the lack of originality on this blog. Finally, Lara sends her greetings:

Advent calendar #3: Details are missing

In 1958, Pauli and Heisenberg were working an a unified theory which is today still the holy grail of particle physicists. Heisenberg gave a talk about their recent results, appearing confident that they had found a unified theory, only technical details were missing. An eager journalist who sat in the audience spread the news about the "world-equation," very much to Pauli's dismay. In a 1958 letter to George Gamov, Pauli commented on Heisenberg's radio announcement: "This is to show the world that I can paint like Titian. Only technical details are missing," illustrated by an empty rectangle.

This alleged all-explaining world equation came about before Yang and Mill's contribution to physics became appreciated. Looking at the Lagrangian in question today, it doesn't seem to be gauge invariant and with a four-fermion coupling won't fare well in terms of renormalizability.

Pauli's letter can be found in the CERN archive.

Friday, December 02, 2011

Advent calendar #2: Pauli and the anomalous Zeeman effect

The Zeeman effect is the splitting of spectral lines in an external magnetic field, first observed by Pieter Zeeman in the late 19th century. The magnetic field removes a degeneracy between electron shells with different magnetic quantum number. By 1920 that was fairly well understood, unfortunately most of the observed atoms showed much more complicated spectra than expected. This became known as the "anomalous Zeeman effect" and caused the theoretical physicists of the time quite some headache. We know today that the additional splitting is due to the electron spin, but it was still a decade till Dirac would write down the equation for spin 1/2 particles that is now named after him. Recalling the time in 1946, Wolfgang Pauli wrote:

“A colleague who met me strolling rather aimlessly in the beautiful streets of Copenhagen said to me in a friendly manner, “You look very unhappy,” whereupon I answered fiercely, “How can one look happy when he is thinking about the anomalous Zeeman effect?””

Thursday, December 01, 2011

Call to readers: Send us your favorite physics anecdote!

Reminded by a recent comment, Stefan and I noticed that time has come to open the first door on the advent calendar. This year, we will have a daily anecdote from the lives and works of well-known physicists. These are all quotations or stories that many of you will be familiar with from your physics lectures, but I hope for the rest of our readers it will be a little daily entertainment one the way to the holidays. We also have a few anecdotes that while widely known I learned are actually fabricated.

Unfortunately, Stefan's and my brainstorming only brought up 19 items! So we need you to help us out: Send us your favorite physics anecdote or quotation (if possible with source), or we'll run out of stories a week before Christmas. To save an element of surprise for our readers, please do not post it in the comments here, but send an email to hossi[@] (remove brackets), subject: physics anecdote. Don't be shy, I won't tell anybody you're reading blogs ;o)

We start today with the 1st anecdote. It's one of my favorites and, I guess, probably also among the best known ones. A journalist who goes under the name Roundy, interviews Paul Dirac. The interview appeared in the Wisconsin State Journal in April 1929 and its complete version can be found on this website.

"Professor," says I, "I notice you have quite a few letters in front of your last name. Do they stand for anything in particular?"

"No," says he.

"You mean I can write my own ticket?"

"Yes," says he.

"Will it be all right if I say that P.A.M. stands for Poincaré Aloysius Mussolini?"

"Yes," says he.

"Fine," says I, "We are getting along great! Now doctor will you give me in a few words the low-down on all your investigations?"

"No," says he.

"Good," says I. "Will it be all right if I put it this way --- `Professor Dirac solves all the problems of mathematical physics, but is unable to find a better way of figuring out Babe Ruth's batting average'?"

"Yes," says he.

"What do you like best in America?", says I.

"Potatoes," says he.

"Same here," says I. "What is your favorite sport?"

"Chinese chess," says he.

That knocked me cold! It was sure a new one on me! Then I went on: "Do you go to the movies?"

"Yes," says he.

"When?", says I.

"In 1920 --- perhaps also in 1930," says he.

"Do you like to read the Sunday comics?"

"Yes," says he, warming up a bit more than usual.

"This is the most important thing yet, doctor," says I. "It shows that me and you are more alike than I thought. And now I want to ask you something more: They tell me that you and Einstein are the only two real sure-enough high-brows and the only ones who can really understand each other. I wont ask you if this is straight stuff for I know you are too modest to admit it. But I want to know this --- Do you ever run across a fellow that even you can't understand?"

"Yes," says he.

"This well make a great reading for the boys down at the office," says I. "Do you mind releasing to me who he is?"

"Weyl," says he.

Tuesday, November 29, 2011

What is all the thinking good for?

The other day I had to write a text explaining the importance of theoretical high energy physics and quantum gravity for the future of mankind. In layman's terms and less than two paragraphs.

I volunteered to do this because my frontal lobe starts shriveling whenever I have to endure somebody working in this area trying to justify their existence by confidently explaining that spin foams will one day dramatically improve the iPhone or so.

Okay, I'm exaggerating. But as I wrote previously it saddens me considerably that knowledge for the sake of knowledge doesn't seem to count as progress anymore. It's not that I don't value technological progress, I just don't think that's all that can “benefit the future of mankind.” As much as I criticized Slouka's article “Dehumanized”, I agree with him that we should stand our ground rather than adapting to external pressure that asks for material short-term outcomes. I finally wrote the following.

“What are we made of?,” “Where do we come from?,” and “What are the laws of Nature that we conform to?” are fundamental questions about our existence that scientists have studied for thousands of years. The quest to answer these questions and to understand the place of mankind in the vastness of the cosmos has lead to a great many of technological improvements. Material prosperity is a, welcome and desired, result that better knowledge of the fundamental laws of Nature brings. But knowledge by itself has also an immaterial value that feeds our desire to understand the world which brought about planet Earth and conscious life on it.

In the last century we have made dramatic progress with our understanding of space, time and matter, but open problems in today's best theories tell us that our knowledge is incomplete. New observations that can guide our learning have moved to very high energies and large distances. It is subject of our research in the areas of high energy physics, quantum gravity, and cosmology to combine the requirements of mathematical consistency and compatibility with observation to learn about the earliest moments of the universe, the elementary constituents of matter, and the structure of space and time itself. Among the most exciting and unforeseen recent insights is the connection between this research and condensed matter physics that is one of the focus areas at Nordita.

Nordita's website btw has undergone a general overhaul and is now remarkably improved.

You can go and shatter my world view by telling me the actual reason you're working on quantum gravity is that you want to become a billionaire with a new and improved GPS that locates your car keys with a precision of a Planck length.

Sunday, November 27, 2011

New Template

As you can see, we have finally switched to the new blogger template. Feedback is welcome!

Wednesday, November 23, 2011

Book review: "Impossibility" by John D. Barrow

Impossibility: The Limits of Science and the Science of Limits
John D. Barrow
Oxford University Press (1999)

In his book "Impossibility: The Limits of Science and the Science of Limits" John Barrow has carried together everything that sheds light on the tricky question what is possible, practically as well as conceptually. It is an extensive answer to the question of FQXi's 2009 essay contest "What is ultimately possible in physics?" but takes into account more than just physics. Barrow also covers economical, biological and, most importantly, mathematical aspects of the question what we can and can't do, what we can and can't know.

The book discusses paradoxa, timetravel, computabily, complexity and the multiverse, though Barrow never uses the word multiverse. The book was written somewhat more than a decade ago, but the summary of eternal inflation and bubble universes, varying constants and the question if it is still science to speculate about something that's unobservable is timely, and Lee Smolin's cosmological natural selection also makes an appearance. Barrow does mention some of his own work (on varying constants and universes with non-trivial topologies) but only in a paragraph or two.

Barrow briefly introduces most of the concepts he needs, but I suspect if you don't already have a rough idea what cosmology and quantum mechanics is about, some sections will not make a lot of sense. He mentions for example the many worlds interpretation in the passing without ever explaining what it is, and has the possibly shortest explanation of inflation and the expanding universe I've ever seen. But if you've read one or the other book that covers these topics you might (as I) be relieved Barrow keeps it short.

The presentation is very non-judgmental. Barrow essentially goes through all aspects of the issue and reports who has contributed what to the discussion, without imposing an opinion on the reader. He also gives an interesting historical perspective on how our view on these questions has changed esp. with Gödel's contributions. However, the writing reads more like a review than a book in that it lacks a narrative, and Barrow also doesn't offer own conclusions, he just summarizes others' arguments. I don't mind so very much about the lack of narrative since I have grown a little tired by the current pop sci fashion to make up a story around the facts so it sells better, but I'd have expected some original thoughts here or there. It is also unfortunate that the book is very superficial on some topics, for example time travel and free will, and if you know a little about that already you won't hear anything new. On the other hand, if you just want a flavor and some references for further reading, Barrow does a good job. I ceartainly learned about some aspects of the possible and impossible that I hadn't thought about before.

Barrow's book is well structured with a summary at the end of each chapter and a final summary in the last chapter. This is very convenient if you put the book down and only pick it up again a few months later and need a reminder what you've already read.

I've been reading for a while on this book. Since 2008 in fact, if I believe the receipt. The reason it took me so long has very little to do with the actual content of the book which, now that I managed to finish it I like very much, and more mundanely with the representation of that content. The book is printed in tiny and in addition the print is crappy, so I get tired just by opening it and looking at a page. It has a few illustrations that are very helpful and to the point, but not particularly inspired. There are also a few photos. As you can guess however, Hubble Deep Field in a crappy black and white print on some square inch isn't too compelling, and it's difficult to see the Château in Magritte's Château de Pyrénées.

Taken together, you may enjoy this book if you are interested in a summary of aspects of the possible and impossible, but you would be disappointed if you're looking for an in-depth treatment of any particular aspect. The book is well written, though not very inspired, and the scientific explanations are well referenced and, for all I can tell, flawless. I'd give four out of five stars if I had stars to give.

Saturday, November 19, 2011

Google Scholar Citations

Google Scholar has a new feature, Google Scholar Citations, that allows you to generate a profile page with your papers. It also lists citations and calculates the infamous h-index. Have a look at my profile here to see if it's an interesting feature for you.

Is it?

To set up a profile page, you first need a Google account. If you already have one, it takes like 2 minutes or so. If you set up your page and enter your name, you'll be offered a list of papers that might be yours, that you can then edit. Mine was pretty good, probably because my name is not very common. A few papers seem to be missing, some listed items weren't papers but deceased websites that I wrote a looong time ago, and my research statement also appeared, but by and large it worked well.

The citation count is not exactly the same as on inSPIRE. In some cases Google Scholar counts more, in other cases less. It's not clear to me what causes the difference.

And my dear husband is evidently author of a paper with 3990 citations. Yes, I am very proud of him :o)

Friday, November 18, 2011

Spreng's triangle

There, I've done it again. I came across some figure in the passing and ended up digging out the original reference in an attempt to make sense of it. In this case the figure is the energy-time-information triangle, proposed by Daniel Spreng in 1978, also known as Spreng's triangle. It supposedly conveys the message that new information technology (whatever that was in 1978) allows to save either time or energy, or a combination thereof. Clearly, I thought, the paper was written before the dawn of Wikipedia...

Spreng has a background that is noteworthy. Trained as a physicist, he later worked as engineer and developed an interest in economics. His triangle is an attempt to connect these areas, and as such very interesting. The example he starts with is purely thermodynamical. A reversible process, without loss of energy, would take an infinite amount of time. Any faster, and the process becomes irreversible. The faster it is, the more energy is needed (at least in the examples Spreng discusses). So there is a trade-off between time and energy that carries over to manufacturing. Information then comes in as an improved technology that makes the process more efficient, and so, more information saves time or energy. That is the basic idea.

Spreng's original paper is here, but I couldn't get access to it, so I settled for the 1993 remake and the following is my summary. You can find the original version of Spreng's triangle on page 13 of this file. I've redrawn it for your convenience, click to enlarge.

Spreng's Triangle

Spreng's triangle is a plane with 3 axes at 120° to each other. The 3 axes are energy (E), time (T) and information (I) respectively. I have drawn lines with constant time in blue, constant information in red, and constant information in green. In the lower right E=0 corner, that Spreng refers to as the "starving philosopher," one needs no energy, but has an infinite amount of time and all the information in the world. In the lower left, I=0, corner, that Spreng refers to as the "primitive man," one has no information and needs an infinite time to get anything done with maximal energy. In the upper corner, the "industrial man," one has plenty of information and energy to get things done in zero time. The corners are however unrealistic limits that shouldn't be taken too seriously, they're just to show the trends if you move around in the diagram.

Now to define a point in a plane you only need two axes, so the relevant statement here would be that all possible points of combinations E,T,I lie in a plane. I say "would be" because I will argue in the following that though superficially plausible and appealing, I don't think it is actually the case.

In his paper, Spreng discusses in which way energy, time, and information partly substitute for each other from several different aspects.

At some point, he claims for example that in industrial countries on a national level working hours substitute for energy use, citing himself in mentioned earlier paper that I had no access to. So I plotted the working time per year per worker from this table, against the annual energy consumption per capita from this table (in kilogrammes of oil equivalent per year).

I don't know about you, but I can't see any correlation or anti-correlation in that. Well, the data I used is from 2003, so, possibly 40 years ago that looked different, but I can't say I am very convinced. However, this turns out not to be of much importance later, he just uses this because he wants to send a message that civilization should slow down the hamster wheel (invest time) to instead save energy:
"Whether the time saved is simply used to produce and consume more, or whether some saved time is set aside as time for cultural development is of prime importance."

One easily sees from Spreng's discussion, that the "information" he is referring to is ill-defined. To be fair however, it does become clear that he is talking about manufacturing processes and their improvement. So Wikipedia isn't really a counterexample. At some point he specifies information to mean 'relevant' information, yet one doesn't know relevant for what. Maybe it's the information needed to decrease energy or time, but then the argument becomes circular. I think the name "information" is very misleading. What he seems to mean is something like the complexity of a technological process. Not that this is better defined.

However, just when I was about to throw the paper in the garbage, Spreng goes and admits that the "relevant information" is totally ill-defined and pulls the following trick that helped me to make more sense out of his triangle. He says, let's just consider information as an unknown parameter and assume it is measured by the market: "[T]he market measures the information content of goods and services." So, let Y be the market value of a good or service, then he defines information (I) by the following equation
    Y = pL L+ pE E + I

where L is input to production of the good in working hours, pL the price per hour, E is the energy input in some units, and pE the price for that energy unit.

That would indeed define a surface if this equation would be fulfilled, so the question is, does it work? First, we note that this equation almost certainly isn't fulfilled for goods with cultural value like, say, Marilyn Monroe's dress. I don't see what difference it should make for the right side of the equation whether Marilyn or I wear a dress before auction, yet I have some doubts anybody would pay me some million bucks for that, so it does make a difference for the left side of the equation which is no good.

So then let's look at goods without cultural value, if such exist, maybe a banana will do. Still, something seems to be really funny with this equation. The alleged market value of the good doesn't at all depend on supply and demand for that good. I mean, I don't know a lot about economics, but if you're growing bananas in your backyard with input E,I,L and suddenly all bananas in Brazil fall victim to epidemic monkey obesity, your backyard bananas would be in high demand and up goes Y without any change to the right side of the equation.

This is not to say that it is not possible to make sense out of Spreng's triangle, but at least from what's in his 1993 paper it seems to me it would take more work to integrate this idea with economics. Spreng concludes his paper with the words
The importance of new information technology, NIT, in respect of future energy use can hardly be overstated. However, NIT can do two things. It can be used to substitute time by information or to substitute energy by information. NIT can, in other words, both be used to speed up the pace of life (work and leisure), thus promoting a society of harried mass consumers, or it can be used to conserve precious natural resources (energy and non-energy) by doing things more intelligently and improving the quality of life without adding stress to the environment. It is up to the society as a whole, politics of course included, to decide which of the
two roads are taken.”

You could then summarize my criticism as these are not the only two roads. Your NIT can also cost you more energy and more time. Like this damned Windows that never seems to finish updating and keeps popping up a message that I have to restart.

Bottomline: Plausible ideas are the most dangerous ones.

Monday, November 14, 2011

The Oscillating Universe

I came across this short story “The Oscillating Universe” by Dennis E. Piper, published in The Observatory, Vol. 97, p. 10P-10P (1977), (PDF available here), and thought you might enjoy it:

One day the Professor called me in to his Laboratory. “At last I have solved the equation,” he said. “Time is a field. I have made this machine which reverses the field. Look! I press this switch and time will run backwards run will time and switch this press I. Field a is time.” Said he, “Equation the solved have I last at”. Laboratory his to in me called Professor the day one. “For heaven's sake, SWITCH IT BACK,” I shouted. Click! Shouted I, “BACK IT SWITCH, sake heaven's for.” One day the Professor called me in to his Laboratory...

Sunday, November 13, 2011

Nerdy Riddle

What am I?

In the mirror I see three,
ψ is always part of me,
I am always positive
And like the I with double f.

Thursday, November 10, 2011

Open positions at NORDITA

Yes, it's this time of the year again... the time of writing applications. NORDITA has some open positions, and it's a great place, so make sure to have it on your list:

We have about 5 postdoc positions in the areas of astrophysics and astrobiology, atomic physics, biological physics, condensed matter physics, gravitation and cosmology, high-energy physics, nuclear physics, and statistical physics. These are 2 year positions and successful applicants can do their own research, they will not be assigned to a supervisor. The job description is here, and the application form is here. The Deadline is November 15th, so it's time to upload your files now and hit submit.

We are this year also looking for an assistant professor in theoretical condensed matter physics. The job description is here, and the application form is here. The deadline is November 22nd.

If none of that is for you, NORDITA also has a visiting PhD student program. It says in the announcement that this program is primarily intended for PhD students from the Nordic and Baltic countries, but students from other countries will also be considered, so don't get discouraged if you don't know where the Baltic Sea is. Applications will be accepted between November 15 and December 15, the application form is here.

As you know, I am currently on parental leave, but if you have questions about NORDITA, I'll be happy to answer them. Write me at hossi[at]

Wednesday, November 09, 2011

New constraints on cosmic strings from the South Pole Telescope

Cosmic strings are stable, one dimensional objects of high energy density that might populate our universe. Cosmic strings can arise in quantum field theories and would form networks that extend throughout the universe. They were discussed three decades ago as a possible origin of cosmological structures, but fell out of favor when that was not compatible with data.

Cosmic strings received renewed interest however since they might appear also in the early universe if superstring theory is taken into account. No longer thought to be necessary to explain present day observational cosmology, the question is now how tightly constrained a possible contribution of cosmic superstrings is and if they may become observable in the soon future, when looked for in the right place with the right means, thus providing a long sought for hint that string theorists are on the right track. For more details, see my earlier post.

A recent paper has now put forward new constraints on the density of such string networks
    Cosmic String constraints from WMAP and SPT
    By Cora Dvorkin, Mark Wyman and Wayne Hu

The brief summary is that the have taken into account new data from the South Pole Telescope and not found anything.

The somewhat longer summary is that cosmic string networks leave an imprint in the anisotropy of the Cosmic Microwave Background (CMB) by actively generating perturbations, even after recombination. Most importantly, they act as lenses for the CMB light, which makes a contribution to the spectrum at large multipole moments or small angular size respectively. See here for an explanation of the CMB anisotropies. The recent measurements from the South Pole Telescope have now much improved the previously available data at large multipole moments. The new data is however perfectly consistent with a string-free universe, which allowed the authors of the above paper to derive improved and tighter constraints on models with cosmic strings.

They are careful to point out however that their constraints directly apply only to the most straigh-forward model of cosmic string networks, and that there are more complicated models (in which cosmic strings are merely meta-stable or there are different types of strings) for which the constraints would look different. In any case, this is yet another negative result for the phenomenology of string theory.

Monday, November 07, 2011

What are natural units?

I noticed that I confused some readers by referring to temperatures in GeV and distances as the inverse of an energy. 15 years ago, when I first learned about natural units, it seemed really fishy to me. Now Stefan has to remind me on occasion that a second is not a distance, and an entropy is not dimensionless. Since I've experimented lately with some new software, I put together a few slides on the use of natural units and youtubed them.

At 3:20min it should be 5000K, not 500K, sorry about that. At 3:30min, Lara tried to eat the keyboard.

Wednesday, November 02, 2011

Grassroot funding for science: A good idea?

Yes, I do give money to homeless people in the street. And, yes, I do on occasion donate to charity. Yet I am divided about the benefits of recent crowdfunding services that promise to help researchers to directly raise public money. Some of these services that collect money are dedicated to specific research areas, others are broadly defined, and most are US-based. Here is a selection:

The Eureka Fund is a U.S. 501(c)3 non-profit organization that collects money for energy and environment research. Proposals are reviewed by a scientific advisory board. If you look at the list of projects and the donations received, the success is not exactly stellar, even though Eureka Fund was featured in the NYT in April this year.

Fund Science is another US based micro-funding organization. According to the brochure, they have applied for 501(c)3 status. They are dedicated to help funding young researchers and pilot projects who have difficulties obtaining funding in other ways. In the first round however, they invite proposals only for "doctoral students pursuing hypotheses related to the pathogenesis or modeling of diseases including Crohns and Familial Mediterranean Fever."

A broadly imagined attempt is, but the website is mostly filled by placeholders instead of content and nothing seems to be happening there. This is funny since Joanna Scott from Nature Network reported last year that the initiative was on its way. Maybe something went wrong there. The Facebook site and Twitter feed are equally deserted.

Then there is the SciFund Callenge, funded by two biologists in California. This fundraising agency runs through RocketHub, a crowdfunding organization based in New York. Maybe because they didn't attempt to reinvent the wheel of crowdfunding, their project list looks decent.

One last example: OpenGenius, which has been celebrated in the press, has an optimistic vision in which scientists and funding agencies propose projects for public funding and the projects are peer reviewed by a "global and highly motivated community." This project is noteworthy because it seems to be not US-based. The website suffers from a certain lack of actual information, but amounts of money are named in EUR and the partners are all Italian.

Needless to say, I think it is a terrific idea to make use of a simple interface that enables researchers to raise some additional money, may that be to replace the ancient lab fridge or to organize a conference. Much like giving some Euros to the homeless guy in the street, money serves to make life a little easier and the day a little brighter.

But beyond little extras, funding research by appealing to the public is not a good trend. It doesn't solve any systemic problem, much like dropping some Euros into a hat doesn't get homeless people off the street. The primary problem with scientific funding today is a lack of risk-taking and commitment: The ideal research project doesn't take more than 3 years to complete and you know the outcome before you've even started. If one would listen to the general public what projects are worth funding it would just reinforce the problems: Most people want to see immediate and tangible outcomes of their investments. That this doesn't work for basic research is exactly why so much of it is tax funded.

It adds to this that the crowdfunding approach puts at advantage research that can be easily decorated with pictures and produced in a video. If your project is about finding the best milk substitute for orphaned kittens it will score better than, say, the kappa-deformation of the Poincare Hopf algebra on discrete non-metric spaces in arbitrary dimensions. That might seem like an extreme example, but it isn't hard to predict that most of mammalian biology and medicine would produce better videos and more catchy pitches than mathematics or theoretical physics. And alien biology of course... Click to read whole comic.

Via Bad Astronomy. I didn't find it particularly funny. It's more in the category sad but true.

Giving to charity is much more common in North America than it is in Europe. An oversimplified summary is that Europeans pay more taxes and believe in representative democracy while Americans like the idea to distribute the money themselves and mistrust their electees. So it isn't much of a surprise most of the examples above are US based.

There is no generally right or wrong way to invest in non-profit organizations; it depends on the aim. Yes, donors chose. But the big question is how well they chose to invest their money and if not channeling of investment through expert committees puts money to use better. There are some cases where crowds are wise and chose wisely. And while the right circumstances for crowds to make wise decisions are still a subject of research, it seems to be clear that one needs a well-posed and concrete question to begin with. In addition, one person's decision shouldn't be affected by the choices others have made. Otherwise the rich will just get richer. These are conditions not fulfilled when it comes to judging on the promise of a research project.

Without knowing the status of a research field one has no way of telling if an investment is good, and this is not a knowledge one obtains by browsing a video collection. Or look at medicine with its many "orphan diseases" - not diseases of orphans, but all those illnesses you have never heard of because no Hollywood star fell victim to it. Where you invest best should depend on how promising a research proposal is, and that potentially in the course of some centuries. Not on what's currently on TV.

I am not saying the general public is dumb. I am talking about a lack of knowledge here, and a lack of time to obtain that knowledge. Pop sci gets you only so far.

Via Moshe. I did find that one hilarious indeed.

Then there is the problem that slopes may be slippery. I can just see us ending up in a position where scientists are expected to use crowdfunding for their research. And that will not only be an ineffective distribution of money because said crowd is prone to like projects for the wrong reasons, but also because it takes up more of the researchers' precious time for producing a fancy proposal that will appeal to the public. And then somebody still has to do the reviewing.

Summary: Crowdfunding science is a good idea to add additional support to underfunded missions or to enable small projects. It is not a good idea to draw upon the public opinion to fund research projects from scratch. It might appear as if public money is put to good use, but that use is likely to be very inefficient and misdirected and doesn't actually solve any systemic problem. If you must, go occupy Wall Street, vote, and make sure your taxes are put to good use.

Sunday, October 30, 2011


Lara and Gloria are now 10 months old. They can both stand as long as they have something to hold on to, and they take little steps along the walls. Yesterday Lara dared to take her hands off the table and surprised herself by standing, wobbly, but all on her own.

The babies' first visit at the dentist featured a doctor informing us that they don't yet have teeth and got us two tiny toothbrushes and a booklet that promises to explain everything you ever wanted to know about baby's teeth - as long as you speak Swedish. Since Lara prefers my thumb over her own, I can testify the first tooth is now well on its way, but we're still waiting for it to see the light of the day.

Recently, the little ones have developed an interest in books and chewed to pieces Dan Brown's "Da Vinci Code," and Stefan has taken on the task of teaching the babies some physics. Since a week or so, Gloria takes delight in bringing her toys to us, just to take them back immediately. It becomes increasingly noticeable that the girls now understand quite a few words, especially the essentials yes, no, good, bad, come, play, milk, daddy.

Lara and Gloria have coped well with the flights to and from Stockholm, much better than Superdaddy who has developed a contact allergy to Scandinavian Airlines SAS. The Lufthansa-end of the trip in Frankfurt is flawlessly family friendly. The SAS-end in Arlanda is a complete disaster. Despite the twin stroller being clearly marked for 'Delivery at Gate' it ended up on the oversized baggage belt and Stefan had to carry the baggage, the baby seat and the two girls through the airport, much to the amusement of SAS staff.

Upon inquiry, we learned that in the late 19th century a 73 year old labor union member strained an ankle when lifting a bag tagged as gate claim. Or so. Ever since then, employees at Arlanda airport refuse to bring anything exceeding 7kg to the gate, including strollers. Not that anybody bothered to inform us about that or offered any help. We for certain will have reason to celebrate if Lufthansa takes over SAS as rumors say.

Yes, parenthood changes you. I for example have developed the unfortunate habit of looking into stranger's noses to see if there's something in need of being picked out. Stefan meanwhile has worked on a theory of snot clumping according to which the size of a snot does not depend on the nose. He's now collecting data ;o)

Thursday, October 27, 2011

The future of the seminar starts with w

I've learned a new word: webinar. Stefan has had a few. Maybe it's contagious.

A webinar, so I've learned, is a web-based seminar. It's a hybrid of video conference and desktop sharing. If you know the International Loop Quantum Gravity Seminar (ILQGS) series, this is the pleistocenic predecessor of a webinar. To take part, you download the slides online prior to the seminar, then dial in to hear what the speaker has to say. One thing he'll be telling you is when to go to the next slide.

A webinar now makes use of advanced file-sharing. Somebody plays the role of a moderator who shares a desktop, not necessarily his own, with all participants, for example the powerpoint presentation of the speaker, but it might also be a demonstration of a software or pictures from your latest trip to the pleistocene or whatever. So, you don't have to switch slides on your own and can pleasantly doze off. Just take care not to hit the keyboard for a webinar is interactive and you might accidentally ask the question "Ghyughgggggggggggggggggg?"

In principle one could stream the audio right along with the desktop and also combine it with a video. However, sharing videos of the participants has limits both at bandwidth and feasibility. If you're giving a seminar with an audience of 100 people, you neither want nor need a video of every single one picking their nose. Much more useful is the option to virtually 'raise a hand' and ask a question, either by audio or by a chat interface.

The webinar interface that Stefan has made some experience with is called webex. In these webinars that Stefan has attented, the audio was not streamed along with the desktop sharing over the web. Instead, participants submit a phone number at which the software will call them. That has the disadvantage that you have to be on the phone in addition to sitting at the computer. (You also need to have a phone line to begin with.) It has the advantage however that if the web connection breaks down you can still try to figure out the problem on the phone. Webex is not a free service - I suppose one primarily pays for the bandwidth that allows many participants since desktop sharing and video conferencing with a few people is doable on Skype also. Google brings up some free offers for webinar software, but I don't know any of them. Let me know if you've tried some of these free services, I'd be interested to hear how good or bad they are.

From the speaker's side the situation requires some adaption if one is used to 'real' seminars. One has to stop oneself from mumbling into the laptop. For pointing at some item, one has to use the cursor which is possible but not ideal. One would wish for an easy way to enlarge the icon so it is better visible.

From the side of the audience there's the general temptation of leaving to get a coffee and forgetting to come back because who will notice anyway. One is also left wondering how many of the participants are sitting in bed or have just replaced themselves with a software that will ask the occasional question. It is actually more a comment than a question...

From both sides there is the necessity to get used to the software which is typically the main obstacle for applications to spread.

If one wants to combine a webinar with a real seminar, new technological hurdles are in the way but they aren't too difficult to take. The shared desktop can be projected with a beamer as usual, the audio needs to go on a speaker. The question is how to deal with 'real' audience questions. This requires a good A/V equipment at location.

In any case, the technology is clearly there and one already finds some webinar offers online. The APS for example has some webinars with career advice, and Physics World also has a few listed. Most of the webinars that I have come across so far are however software demonstrations. But after increasingly many institutions routinely record seminars and make them available online, I think webinars are the next step that we might see spreading though academia. I for sure would appreciate the possibility to easily log in to one or the other seminar from home while I am on parental leave.

However, if the nomenclature develops as it did with weblogs, we'll end up sitting in binars, you're either in or you're not.

Have you made experience with a webinar? Would you consider attending, giving, or organizing one?