Sword Blades

"He took a shagreen letter case
From his pocket, and with charming grace
Offered me a printed card.
I read the legend, "Ephraim Bard.
Dealer in Words." And that was all.
I stared at the letters, whimsical
Indeed, or was it merely a jest.
He answered my unasked request:
"All books are either dreams or swords,
You can cut, or you can drug, with words.
My firm is a very ancient house,
The entries on my books would rouse
Your wonder, perhaps incredulity.
I inherited from an ancestry
Stretching remotely back and far,
This business, and my clients are
As were those of my grandfather's days,
Writers of books, and poems, and plays.
My swords are tempered for every speech,
For fencing wit, or to carve a breach
Through old abuses the world condones.
In another room are my grindstones and hones,
For whetting razors and putting a point
On daggers, sometimes I even anoint
The blades with a subtle poison, so
A twofold result may follow the blow.
These are purchased by men who feel
The need of stabbing society's heel,
Which egotism has brought them to think
Is set on their necks. I have foils to pink
An adversary to quaint reply,
And I have customers who buy
Scalpels with which to dissect the brains
And hearts of men. Ultramundanes
Even demand some finer kinds
To open their own souls and minds.
But the other half of my business deals
With visions and fancies. Under seals,
Sorted, and placed in vessels here,
I keep the seeds of an atmosphere. "

Amy Lowell, Sword Blades and Poppy Seed

Read the full text at Project Gutenberg

Atomic Flowers

Sculptures by Brent Collins:

Though I'm a nonmathematician, my work originates in intuitions which have consistently led to an art of visual mathematics. Such an art obviously has a special resonance for scientists and mathematicians, but being visual, it can be just as immediately engaging for general audiences. Its patterns invite mathematical analysis, but require none, and need only be seen as music need only be heard. The elegant economy found in the forms and dynamics of nature has always been an inspiration to me, and I have aspired in my work only to that profundity which might arise from subtle analytic rigor, much in the manner of science. Images of sculptures I have created over the last fifteen years can be seen in the following galleries. The galleries are devoted to representative works from distinct paradigms appearing in chronological succession up to present.

For more, see this website.

PI day

Today is march 14, or 3/14, as Americans will write - that's π day! It is such an important date that it even has its own website! Unfortunately, if you have a look at the first few decimals of π, you can see that you can't celebrate the π instant at 3 pm something in the afternoon, unless you use a quite awkward scheme to split the hour...

By a curious coincidence, π day is also the birthday of Albert Einstein: He was born on march 14, 1879, in this house in Ulm in southern Germany (the house was destroyed in 1944, so you cannot visit it any more):


(Source: Albert Einstein in Ulm)

As the celebrations of his 125th birthday, and the 100th anniversary of his Annus Mirabilis have brought us many many great websites about Albert Einstein, there is no big point in repeating here anything of all you have for sure read many times.

But did you know that Einstein himself might have had some trouble to recognise PI π in his birthday? As every child learns in school in Germany, dates are written in the form day, month, year. So, Einstein has written his birthday most probably as 14. III. 79, following the conventions of his time and using roman ciphers for the month. That's good to know if you want to make sense out of the date 4. I. 19 - it is January 4th, 1919. That's no special date, it just happens that Einstein lectured about "ponderable bodies" on that day, as he has written down in his lecture notes:


(Source: Albert Einstein Online Archive)

The lecture on 9.11. (that's November 9th, quite an important date in German history) fiel aus wegen Revolution - it was was cancelled "because of revolution"...

Coming back to Einstein and the π day, one might wonder whether Einstein's papers are encoded somewhere in the decimals of π. That's the case if π is a so called normal number. Unfortunately, no one knows so far whether π is normal or not, despite ongoing progress on this question.

The inverse question is much more easy to answer: Does π occur in Einstein papers? If we have a look in the famous Ist die Trägheit eines Körpers von seinem Energieinhalt abhängig? (Annalen der Physik 18 (1905) 639, here as PDF, the famous L = mV² paper), this paper gets by without any π! OK, you may say, that's a short paper. What about the Elektrodynamik bewegter Körper (Annalen der Physik 17 (1905) 891, here as PDF - the electrodynamics of moving bodies, the SRT paper)? Surprise, there are only 4 πs in this 30 page paper, and only in relation with one expression for the energy density. If you really want to get rich in π better invest in Über die von der molekularkinetischen Theorie der Wärme geforderte Bewegung von in ruhenden Flüssigkeiten suspendierten Teilchen (Annalen der Physik 17 (1905) 549, here as PDF, the paper about Brownian motion) - I did not count them all.

What can we learn from all this? The special theory of relativity is not transcendental!

Happy π day!

---

TAGS: PI day, Albert Einstein

Good physics is conflict

Last week, The Royal Society for the Encouragement of Arts, Manufactures & Commerce (RSA) organized a debate around the publication of Lee Smolin's book 'The Trouble with Physics' in Great Britain. It was moderated by the Chris Isham, and besides Lee Smolin, the guests were the physicist Michael Duff, and the philosopher Nancy Cartwright. You can download the audio on this website, and find a report on the evening here.

*yawn*

I meant to write a concise summary of this debate about, around, and with troubled physicists since Clifford picked up the topic and stormed another teacup. What I think about the alleged trouble with physics, I've written so often, you can read this, this, this, this, this, this, or this. And, if you really want, also this, and this.

However. I find it hard to get sufficiently upset, and since it's after midnight I'll keep it short. On the one hand I fail to see what is insulting about the book. If the book is insulting for anybody, then it is insulting for all of us theoretical physicist, and for the simple reason that it's never nice to be forced to face the own weaknesses. On the other hand, I agree with Clifford that this debate should not have been lead in the public. One way or the other, what was done was done, and what we should think about now is the future not the past, so could we please move on.

Essentially, the most interesting things were said by Nancy Cartwright. Okay, she used too many words that end with -ism, but she made the important point much better and clearer than Lee Smolin or Micheal Duff (1:02 min):

Physics must be open, critical and responsive [...] Physics, good physics, is conflict.

Therefore, instead of a lengthy writing, here is my summary:

WildWestSound.mp3 (~ 1.4 MB)

Have fun. (Background music: Scooby Shack by Fun Loving Criminals).

#34

This morning I looked out of the window and I saw the neighbour's roof.

I mention this because I haven't seen the roof for several months. All I've seen is snow, snow, snow. The most annoying aspect of the snow was that I couldn't find my parking lot, the numbers being printed to the pavement. Repeatedly, I must have chosen the wrong spot, and found complaints on my windshield telling me I had parked on a private lot and would I please vanish. I put a precautionary note on my car saying, if this is not #34, and you are able to find it, please use mine.

And here it reappeared, ladies and gentlemen, #34

Why I am a physicist: Stefan Scherer

After following the guest posts of our inspiration series for some weeks, Sabine pointed out that despite being a contributor of this blog, I haven't told my story. So, let me try to explain, how did I come to be a physicist, and what does it mean to me?

Sometimes I ask myself, am I a physicist? I have studied it, I have even a PhD in physics, but I am not currently following a research or academic carrier. Now, this is a situation shared by many physicists - probably more than in other sciences. Many of them find jobs in software, or, especially in places like Frankfurt, in finance. I have been very lucky, finding a job where I am keeping touch to what is going on in the science, at the crossroads of two passions of mine: physics and books. I currently work in the editorial office of a multi-volume reference work covering all areas of physics. So, I am keeping contact to physics more than most other physicists outside academia. Point I want to make, being a physicist is not so much a description of what you do, but of the educational path you have taken, and, first of all, of a certain curious, and at the same time analytic, way to look at the world around us.

On the other hand, when I look back and try to see why and how I became what I am now, there are many contingencies that have brought me where I am, and many junctions that may have lead to other directions.

When I was a kid, there may have been signs that I may become s scientist, but not specifically a physicist. I was very curious about nature - my mother was amazed that I could name all the birds in the big garden around our house, and even accurately draw pictures of some of them. Later, I remember, I was fascinated by the TV series of Jacob Bronowski and Carl Sagan, and vividly read the accompanying books my parents had offered me. As a teen, I discovered the volumes of the TIME-Life Science Library series my father had subscribed to years earlier, and I read again and again about Matter, the Planets, or Mathematics, understanding a little more every time. And I was quite frustrated by the Scientific American, which I found extremely interesting, but which was way above my head. All this may have qualified me for very different paths, and indeed, in high school, when thinking about what to study later on, I sincerely considered many options: For some time, wanted to go into computer science, following the steps of my uncle, and learning more about artificial intelligence which was very much en vogue then. But I also was thinking about studying archaeology, and even to become an interpreter - after all, I could learn foreign languages with ease, and the institutions of the European Union in Strasbourg, Luxembourg, and Brussels were not far away from the place where I grew up.

In fact, I do not remember how and why I took the decision to inscribe in physics. In the year before Sabine left Germany, she made a video for the Christmas party of the physics institute in Frankfurt, where she interviewed people about all kinds of things - it was a lot of fun! When she pointed the microphone at me, I replied without hesitation to her question that I had studied physics because of Supernova 1987A. Though this sounds like a good answer, it is most probably one of those reconstructions which our memory creates at hindsight to provide us with a straightforward story. On the other hand, there is for sure some truth to it, since I had developed a big interest in astronomy at that time, and the Supernova was a prime event in that year. There was no astronomy department in my "hometown" Saarbrücken university, so choosing physics probably was a logical step.

Saarbrücken is a small university, with the physics department focussing on condensed matter physics. I was quite impressed by the course on theoretical physics offered by Arno Holz, and after following closely his seminar on topological defects in condensed matter physics, it was clear for me that I would join his group for my diploma. Unfortunately, Arno Holz didn't live to see me finish my thesis. In a sense, his untimely death pushed my path through life in a new direction: The lecturer who took care of us students had close connections to a scientific publisher. He had translated several books, and was then looking for support with the translation of a text on the electronic structure of materials. With my faible for books, I thought this was a very interesting job, and did it. Indeed, I liked it so much that after my diploma, I decided to look for a position in publishing. I had luck and found a post with a publishing house in Frankfurt, where I immersed in the then new technologies of electronic media and prepared the German edition of a HTML based physics course.

Working with the quite small Frankfurt publisher, it was inevitable to learn to know Horst Stöcker, who was not only one of the "star authors", but had his office at the institute for theoretical physics just across the street, and looked in quite often. When he learned that for my diploma I had worked on phase transitions, he asked me if I would not be interested in investigating the phase transition to the quark-gluon plasma, and getting a PhD in his group. I then knew next to nothing about quarks and QCD, but this was an intriguing option to learn some cool new stuff, and to do some real research. So, over the next long years, I shared my time between the publisher's desk and the physics institute. And this not only earned me a doctorate, it literally widened my horizon: The institute in Frankfurt is quite big, and has collaborations and connections worldwide. There was a constant stream of postdocs and guests from all over the world, and I am really happy that I have had this experience to get to know all these people. And, of course, that I met Sabine, who's now my wife.

This may not have been a very typical career path, but somehow, I think, it fits with me. Still like the teen who was not sure what to study, I have many interests, and get manifold inspirations form friends and people I am interacting with. However, what intrigues me now especially in physics, that's the unity, the same principles and fundamental patterns which show up again and again in such a wide area of subjects, from condensed matter over molecules and atoms to the nucleus and elementary particles. This is just fascinating, and seeing and understanding such connections doesn't lose its thrill the more I know and learn. Being out of university now, I am happy that I have friends who keep me up to date - and that so much information is now available through the internet. There it still is, the endless frontier, and I am just curious and eager to know what it will show.

---

See also the previous contributions to the inspiration-series by

• Christine
• Anne
• Peter
• Kerstin
• Stefan
• Tommaso
• Chanda

and Sabine's related guest post at Asymptotia 'Sabine Hossenfelder: My Inspiration'.

---

TAGS: PHYSICS, PHYSICISTS

Decoherence Dance

On Saturday night, the 'Decoherence Dance' took place in the old PI building on King Street - hopefully the first of many to come. I used the opportunity to test the video option of my new digital camera, and was able to produce the movie below with the appropriately bad quality. I welcome myself to the YouTube generation.

(audio: Word Up by KORN)

Well, the first upload looked even worse. In case anybody knows how to keep the resolution better, let me know (I've already rescaled it to 360 x 240, turned off interlacing, and set the frame rate to 24).

Echo: DDR as a Test Model

This is a copy of my post at the blog to our discussion group 'Quantum Gravity in the Lab?!' about our meeting on March 6th. The discussion was lead by Michele Arzano, and this week's topic was 'Planck-scale departures from relativistic symmetries: test theories and status of predictions'.

---

Michele Arzano arrived as postdoc at PI around the same time as I did, in fall 2006. Before I start explaining what he told us in the discussion this week, let me point out that he's DJed for some while, and had the idea to organize PI's first 'Decoherence Dance' that will take place on Saturday in the old PI building. In case you're around, drop in... Michele has a quite impressive number of works on Hopf-algebras, black hole thermodynamics, and modified dispersion relations. Though he prefers to call these 'deformed dispersion relations' (DDR).

He started with explaining the general idea to confront a (not further specified) 'candidate theory of quantum gravity' (QG) with the real world by use of a test model. Such a test model, he explained, would generally have a 'main feature', and possible 'additional features'. I think of this as parameters which might not necessarily all vanish, but could do so under certain circumstances. An example that he gave later might be a DDR that could but doesn't have to come along with a violation of conservation laws, and the resulting threshold modifications.

Michele then briefly summarized evidence for DDRs from QG.

First, dispersion relations get modified in theories with non-commutative space-times. Such could arise in certain string scenarios, where Lorentz invariance is broken (for a review see e.g. Review of the Phenomenology of Noncommutative Geometry), or the non-commutativity arises through a modification of the Lie-Algebra from standard flat-space symmetries a to a κ-Minkowski Lie-Algebra (for references see e.g. Hopf-algebra description of noncommutative-spacetime symmetries).

Second, evidence for DDRs has been found in approaches from LQG (see e.g. Loop quantum gravity and light propagation, and Quantum symmetry, the cosmological constant and Planck scale phenomenology)

He then defined the test model by generally parameterizing an expansion of the DDR. The coefficient for the first non-vanishing term in energy over Planck energy E_p is the most important one:


Since the expansion parameter is typically less than 10^-16, it is of utmost important whether the first power n is 1 or >1.

This deformation is what he referred to as the 'main feature'. Since this is not a theory, but only a single equation, this might come with additional features like a modification of energy-momentum conservation, or an energy dependent speed of light. Generally, he said, it is an open question whether the dynamics can be described by an effective field theory. The above expansion includes DSR approaches as well as an explicit breaking of Lorentz invariance with a preferred frame.

[At this point Michele had already talked one hour instead of half an hour.]

He summarized two prediction that arise from this approach.

1. In the general case of a DDR the speed of a photon depends on its energy. This means that a signal composed of different frequencies shows an unusual dispersion. Roughly spoken, higher energetic photons are faster than one would think they are. The problem is that this difference in the time of flight is hard to detect, since the ratio of the photon's energy over the Planck energy tiny is for typical photons that we observe. However, a difference in time of flight can add up given that the signal composed of different frequencies travels over a long distance.
   
   If one inserts the typical scales it turns out that γ-ray bursts provide a source that would make such an effect - tiny as it is - observable with the GLAST satellite. The bursts have a high energetic contribution that can reach up to 1 GeV, and a typical distance of a Gpc. In the case of n=1, the accumulated difference in time of flight between the higher and lower energies becomes comparable to the typical duration of the burst itself (of the order milliseconds), and thus potentially detectable. (I mentioned that the energies inserted in the equation were taken in a specific restframe, that of the cosmic microwave background.)
   


2. In case energy-momentum conservation is modified, one obtains a modification of thresholds for particle production. This effect has been used to explain the to-be-confirmed absence of the GZK cutoff for cosmic rays. To briefly recall the issue: cosmic rays are commonly believed to be created from incoming high energetic protons that are not produced in nearby sources. If the protons move fast enough relative to the cosmic microwave background however, they will eventually scatter on the background radiation and produce pions (pions being the lightest mesons). If the threshold for this reaction is crossed, the typical travel distance (mean free path) of the protons drops considerably, and they can not reach us any more. One thus expects a sharp cut-off in the spectrum that should occur for proton energies around 10¹⁹eV (in the earth rest frame. In the center of mass frame this is roughly a GeV).
   
   Whether the threshold is raised or lowered depends on the sign of η. I forgot whether positive or negative would raise the threshold as necessary, sorry. (As Joy pointed out, the experimental situation on the GZK cutoff is far from clear, and there are many issues that have to be taken into account. I mentioned that the energies inserted in the equation were taken in a specific restframe, that of the cosmic microwave background. Yes, I know, I insist on that point. )
   

[Somewhere around here the discussion exceeded 90 minutes. I think I must be the worst discussion leader that the world has ever seen.]

Michele didn't have the time to elaborate on the question whether or not n>1 effects would be observable as well.

In my opinion another test for the test model is whether or not it can be put into a consistent framework. It is unfortunate that this test model still only consists of a couple of equations, and can not be understood as a theory. I think the requirement of having the main- and/or additional features arise from a theory would significantly improve the reliability of the predictions, and help to clarify ambiguities of the model. Overall seen I find the approach interesting, though direct connections to quantum gravity seem to be weak, and more motivations than actual derivations. It is hard for me to judge on whether the discussed features must necessarily arise from certain approaches, or are just a general possibility that one can't (and doesn't want to) exclude. In this regard, I hope that Lee will enlighten us next week.

Suggested literature:

• Introduction to Quantum-Gravity Phenomenology
• Probing The Structure of Space-Time with Cosmic Rays
• Gamma Ray Bursts as Probes of Quantum Gravity
• TeV Astrophysics Constraints on Planck Scale Lorentz Violation
• GRBs Neutrinos as a Tool to Explore Quantum Gravity induced Lorentz Violation

LaTex Test

If you haven't yet sufficient evidence that I'm completely stupid, here's how I spend my Saturday morning: getting upset about people who write how-tos without actually explaining anything. Okay, okay, I'm just a looser with add-ons and I never use Firefox because it just looks ugly. Anyway, here's a test.

Ahm... let's see... hmm.... and now click on the precious button... and...

VOILA!! I did it!! Folks, from this day on, my blog comes with equations :-)

I won't even try to explain how I did that because I for sure couldn't reproduce it. Let me put it like this, it's kind of important you see a monkey in the lower right corner of your eye, for more info go to: Greasemonkey and for one of the annoying how-tos see e.g. here. It won't work for the comments though, sorry, I guess we have kind of a hierarchy problem there.

Great. Now I need a coffee.

Weather report from Waterloo: cloudy and that stuff falling from the sky can't decide whether to be snow or rain. This means spring is coming.

Temporary Display - contd.

Yesterday's post caused some very interesting comments, one of which I want to promote to a guest post. Not just because I'm as lazy as busy, but because Jörg has raised some important points.

---

Jörg Ruppert is a German physicist presently working at the physics department of McGill University, Montreal, Quebec, Canada (since Sept. 2006). This job is his second postdoctoral appointment. He has worked at the physics department of Duke University, NC, USA, for two years after graduating from J.W. Goethe-University, Frankfurt, Germany. His research interests are the QCD phase diagram and related to that phenomena occurring in hot and dense nuclear matter produced in heavy-ion collisions at RHIC and CERN. In his spare time he enjoys discovering the wonders of Montreal.


Yesterday, Bee send me a link to the article by M. Lang in Nature. The title (and the subtitle) of the article sounded interesting ("Temporary display: If you look on short-term employment as a way of window shopping, you could get a bargain"). And I am sure one could have written a nice one page essay about it, the actual article fell short of my expectations.

What the author actually did in the first column was contrasting "German" and "American" points of view on temporarily employment. This was followed by his point of view on the advantages of temporal employment for employee and employer in science.

Since the text was published in Nature under the category "inside track from academia and industry" and therefore has been made part of the discussion in a scientific environment, I feel that I have to respond critically to the article as it stands. While I have no problem with the fact that the author (or in general somebody) has a different view on the issue than I have, I would have a problem if the text remained unresponded. That's why I think that it is a good idea that Bee made it an issue in her blog.

I confess I did not have time to do a lot of research about the author and the circumstances in which the text was written. I also confess that I am one of those who are on "Temporary display" and that therefore my opinion might be subjective and perhaps as biased as the author's one (although biased in a different way I hope).

I also decided against analyzing every part and the total of the text in great detail. I just wanted to let you know what came to my mind while reading it:

I think M. Lang misses the point in the German vs. American discussion of temporary employment in scientific research. While the German job market has always been more regulated (in the sense of unions and legal protection of employees) than the American and while Germans (on average) might tend to emphasize job security when considering the benefits of a job more than Americans, this difference in attitudes is not addressing the main issue for people employed in short-term (say <~5 years) research jobs (in many research fields). I actually think this part of his discussion is misdirecting the whole punchline in which the issue should be seen. Obviously job security is a question in research as in any job, but the specific character of research jobs as opposed to many other jobs might make it even more important in research in the long run:

• Long term projects in fundamental research afford a longer term perspective. That is one reason why (at least (!)) senior scientist should have tenured (or long term) positions. People working on long term position can develop research fields on long term perspectives. People working on short term positions can't do that as effectively.


• Short term jobs are also enforced by funding agencies: senior scientist get grants for a certain period and have to reapply, they can't offer long term jobs to their (former) postdocs unless a research or faculty position is opened by their university/research institution.


• If one wants to see the system of postdoc employment from its best aspects, it might be seen as a setup which wants to help young scientists to work with experts in their research field at other places than where they made their PHDs or where they will eventually get a senior science position. It can be interpreted in the sense of "years of travel" where you gain additional experience after having finished your PHD.

Every single postdoc appointment has to be long enough to allow the person (and his/her collaborators) to substantially profit from his/her stay at every single place.

Switching between short-term employments means moving and adjusting to new places and people. While this can be thrilling and keeps you in an active state of the mind, this also takes considerable time, energy and financial resources. One is tempted to point out that even postdocs are not research machines, but human beings with human needs. What does it mean not to be "tied down with family and financial commitments" and friends? It simple means that you shift (because you decide to in order to gain experience and improve your prospects on the long-term appointment job market) during the postdoc years your commitments towards your job away from friends and family. Many people decide to do that also outside of academia -- but it is a decision and for those among us who value close social bonds to loved ones a tough one. In this context I wonder why the author fails to acknowledge that "family values" might be one of the strongest American traditions (stronger than in Europe at least) and that it is actually difficult to move one's partner over the planet -- especially if he or she wants to develop a reasonable career by him-/herself.


For most of us choosing this path also means making not the most reasonable possible choice (judging only on economic grounds): a postdoc position in fundamental research almost never pays off in dollars and cents (even if you get a long term job). Measured financially most of us could seek much more lucrative job options (also in the long term), I guess. In that sense the discussion of the scientist job market in a reduced economical language might in the end prove counterproductive: if we are only economically justifying our choices then a science career definitively is not the best one after all.

That is not to say we shouldn't pursue a scientific career, but people discussing this career path should have in mind that most folks that have chosen to work there don't have money on their highest priority list - which is not to say that a decent salary is necessary to attract good people to science and science careers.

So what's the rational reasoning for making a postdoc experience (and not opting against it and pursuing another career) to my opinion?

• You love research.


• You want to learn from/ do research with leading scientists in your
  field and go to where they have long term jobs (which also provides scientific networking later on etc.)


• You want to eventually get on a tenure track position towards a "senior researcher" with a long term perspective. (As an Ass. professor in the North American system one is on probation for a long term job -- Nobody I know who is German and knows that system doesn't want to have the assistant professor tenure track system copied into the German University system)


• If the long term perspective is gone (meaning the firm believe that your short term appointment can turn eventually in a long term appointment), than it gets a much tougher journey. And that is the real problem in many fields especially if you have not been clever enough to chose the research topics and places (and last but not least supervisors for thesis/postdoc) that have the full level of publicity in the scientific community. Then it gets tough, even tough to motivate oneself further albeit most people love their research. It is especially hard to keep a positive perspective if you know of other researchers in your field that just fail to get a job because their subject is not on the peak of (temporarily and changing) public awareness of the scientific community -- not because they won't do great research or have a vast knowledge and competence.


• I also think that short term appointments increase the publication pressure (which can mean more quantity than quality in research output) and the pressure to do short term projects. Furthermore looking for a job every one or two year can make the competition fierce. Again: one should value competition in research (in he sense of providing independent checks and keeping the people focused and on the frontier of research), but I think collaboration in science is equally important. The present system favors competition often over collaboration -- probably copying the free economic market system.
  Science should have a different quality than economic life. While competition is the most important principle in order to provide different competing choices of products for the costumer, science should still seek the unique answers meaning truth and advancement of knowledge -- as its ultimate goal -- and should value collaboration equally high.

To my understanding the prospect of long term appointment can motivate short term appointment (and make it justifiable even if one thinks somewhat in an economic perspective).

The author acknowledges this simple fact also indirectly: "it gives them an opportunity to see the scientist in action, before they make a long-term commitment",

Exactly, nobody argues against a research institute putting somebody on temporary 'probation' to test if the person fits in. In addition nobody says that if people stop doing research or do inappropriate things at their workplace that they should be protected by unreasonable laws or regulations from being fired even if they are on long term position.

All what I argue is that a long sequence of short term positions with a fading perspective of long term jobs in research can drive researchers/postdocs and even worse the quality of their research down: may they be from North America or Europe...

---

TAGS: SCIENCE, SCIENCE AND SOCIETY, JOBS

Temporary Display?

"SCENE: A pavement café in a bustling European capital. A forlorn German scientist stares into her coffee. An American friend arrives and sits down.

American: Hey, what's up? You're looking pretty stressed."

That's what I just read an article in the recent Nature issue (Volume 446 Number 7131 p108) by Martin Lang, titled The inside track from academia and industry: Temporary display. The author description says 'Martin Lang is recruitment consultant for Kelly Scientific Resources in Cologne, Germany.'

Essentially, the article elaborates on the allegedly typical German wish for permanent positions (German: [...] But I'd still rather have the stability of a permanent position. I want to stay put until I retire.) In contrast to the allegedly typical American flexibility (American: To be honest, those days are over. It just doesn't happen any more. If the choice is between staying unemployed and trying something different, why not give temping a try? ).

Of course I feel personally offended by that, because I have heard similar arguments for academia, very naively transferred from industry. Martin Lang essentially argues that temporary positions are becoming more common because the job market has changed 'There is no point mourning a job market that has been undergoing dramatic change for several years.' and that we should get used to it 'Both employers and employees are constantly reacting to changes caused by globalization, new technology and shifting scientific and political fortunes. Temporary employment is one reaction to these changes. It is accepted in most sectors as a way to keep staffing levels responsive to fluctuating needs.' And he realizes:

'But to PhD scientists in some parts of the world, the idea of temporary employment can [...] elicit a negative response.'

Now that's really surprising. Well, I can't say very much about industry (actually I can, but would you trust me on that?), so let me stick to academia. The first important point is hidden in the sentence 'So if you're not tied down with family and financial commitments, why not make use of your freedom to exploit the temporary job market?' -- the obvious question is what happens to those who are 'tied down with family'?

Among postdocs the additional problems with this view are:

a) There are just projects you would never start on a short-term employment. And good things take time. If you want your postdocs to do good work, give them a sensible contract.

b) Jumping from one temporary employment to the next is okay for some while. The problem is the absence of long-term positions where you can land. Temping does only work temporarily. It's nothing you want to do for the rest of your life. And being the typical German, I find the spareness of future options genuinely depressing.

c) A long-term contract doesn't mean you are stuck with the people, but you trust in them. That pays off. (It means also you obviously avoid life-time positions, like Professors in Germany, who can't be fired, no matter what.)

d) For the industry, temporary contracts are in many cases just a test run for a possible long-term employment ('For companies that are cautious about bringing in high-level staff permanently, it gives them an opportunity to see the scientists in action, before they make a more long-term commitment.') Where is this option for postdocs?

SCENE: A pavement café in a bustling American capital. A forlorn American scientist stares into his coffee. A German friend arrives and sits down.

German: "Good advice: Never read the 'The-way-I-see-it' column on Starbucks cups. It will most likely spoil your day."

And that's Nemo.

---

See also the follow-up post: Temporary Display - contd.

---

TAGS: SCIENCE, SCIENCE AND SOCIETY, JOBS

Empty Wall

This is a PS to the earlier post Contemporary about the painting that hung in the PI lobby:

After I encouraged as many people as possible to not only tell me they don't like that thing, but to please voice their opinion in the art committee, here is what I found when I came back from LA:

See, every now and then, even a theoretical physicist can help to make the world a nicer place.

I want to ride my bicycle ...

March 6th: Due to heavy winds during the last days, my bicycle has reappeared.

This morning, when I left the house, the outside temperature was -22° C. You know that it is a really cold day when even the Canadians wear gloves on the indoor track. At coffee break I talked to Fotini, who told me it's the month to be away. The funny thing is that every month somebody else tells me it's the month to be away.

@ the anonymous snowboarder in Vermont: I'd be more than happy to ship all the snow over to you. I'll contact Canada Post and ask them for an estimate on the postage fee. I see a huge potential for this procedure. One of you guys in California, could you send some mild sea breezes over here?

Guest Post: Christine Dantas

Try to conceive nothingness.

It is not the modern physical concept of the vacuum, full of energy, and giving rise to ephemeral virtual particle/anti-particle pairs. Nor it is like a blank panorama, something like a flat space-time devoid of matter, since there is no energy, no time, no space, and no mind -- for whatever definition it is worth --, since even self-conception is not allowed for nothingness.

Nothingness stands more elusive than the concept of God. It reigns separate from any possible concept or entity, it is devoid of any realization -- even of itself; it does not belong to anywhere nor anytime to "this world" (or to any other possible world) -- yet, to our intellect it is "there" somehow.

Why exists everything, instead of nothingness? Nothingness should have been the rule. Or perhaps it is, but we do not realize it. We *do* wonder that, before being occasionally constituted into living forms, we *were* nothing, and when we die, we will be *nothing* again. But is it the same thing?

Perhaps, in fact, nothingness reigns. Perhaps, as paradoxical as it may seem, everything is in fact, nothingness revealed to us. And hence, there is no creation, but some odd, inconceivable delusion.

Those rather metaphysical questions bothered me for a long time since a very young age. Such questions do not belong to physics, but it seemed clear to me that, somehow, I could only understand them through science (and to a certain extent, through philosophy), but not through religion.

I mention religion because I was ten years old when I realized that, after staring, every week, during several years, half an hour or more at the image of Jesus Christ in a church of my school (I studied at a Catholic School), repeatedly and full-heartedly in my mind asking for Him to appear before me -- if he really existed --, and not receiving even a glimpse of response back, I could only conclude He did not exist. My intentions were the purest possible, and He never came. Why He would not come before me? I started to become more and more defiant in my requests, until I decided I would no longer pray before sleeping.

It was a hard time for a little girl, very shy, and scared to talk about these events to anyone else. I was very lonely in this mind endeavor, but it was not so terrible that it happened that way. At least, as I see it now.

I was (and am) exceedingly impressed by the fact that I exist, that the Universe exists, and this fact imparted on me, and perhaps substituted the common idea of God deep inside me for something else that even today I don't know what it is. Perhaps, it is nothing after all, but I do not know for now.

Back, during that time, I discovered science-fiction books, and consequently, popular science books. I would say I had two great teachers during this period: Isaac Asimov and Carl Sagan. From reading their books as a teenager, I decided to be a scientist.

It was and is hard to be a scientist for several reasons, but I will spare the reader from this. I will only mention two things that bothered me most for some time. First it was to find out that not every scientist was turned into a scientist for similar motivations that I had (I mean, the search for a deep understanding about nature). Second, that it is hard, very hard, to get a job as a scientist. Specially if you are too romantic and do not see why a large number of papers is "almost" all that makes a career (being very socially driven also helps a lot). My romantic view of science (that what matters is the value of your work and thoughts) is perhaps the most "misleading" and lasting impression that I carry from my childhood's conceptions and endeavors. We do get old and learn something about the "world out there" and adjust as time goes by. But the most important thing to me is to learn not to get corrupted and remain faithful to your own deep motivations.

So every question in fundamental physics concerns me, intrigues me, and it's unavoidably part of my own questionings. Many physicists would not agree on this and would have a much more impersonal posture and highly different motivations and aims. It is not that I think they are wrong (apart from those that look for stardom), but if I am to be entirely faithful to what I am and think, science goes beyond models, numbers, theories and even brilliant ideas. It is about a deep endeavor -- as Carl Sagan wrote once: it's about atoms thinking about atoms. And although we need models, numbers, theories and ideas to "think" over them, what matters at the end is the fact that nature is understandable at all -- as Einstein would add. To understand nature, even in our tiny human steps, requires exquisite intellectual conditions and a life effort of many minds.

Apart from the difficulties, I cannot think of any other activity as intellectually pleasant as the scientific research, except perhaps for music, to which I had devoted myself for some time (as a soprano). I did not chose a scientific career because I was good at maths and physics (I was average, and did much better in composition and arts: in fact, I wrote many science-fiction short stories and poems when I was younger and a SF book, unpublished, entitled "Laplace's Demon"). I chose it because I know of no other convincing and objective way that I could attempt to *understand* something about the Universe and about myself.

Having "acted mostly" as an astrophysicist until now, I really never contributed to the fundamental questions that so much bother me, since I only had the opportunity to look at some tiny details that nature uses to show us on the sky. All I hope is that I still have the time to put my whole energy into fundamental physics. That is my ongoing lifetime aim, even though I am largely unsure on what I really can achieve.

I did not go very far in terms of what many scientists consider as a successful career. If I had followed some prescribed path or formulae, perhaps I would have gone somewhat "far", but would have reached nowhere in terms of what I was initially motivated. And such a "nowhere" certainly would *not* be any closer to the "nothingness" that impelled me first of all! So, what can I say? I have been more or less faithful to myself and I am happy.

So here it is, a little about why I chose science as a career. This text, I would say, reflects the most abstract and nebulous part of my motivations, and just for this reason, I thought it was more interesting to focus on. Thanks, Sabine, for the challenging invitation.

Christine Dantas is a Brazilian astrophysicist working at the Instituto de Aeronáutica e Espaço. She is interested in foundational questions in physics and cosmology. Recently, she found out that she cannot really escape from the blogosphere, so gave in and set up a new blog, Theorema Egregium. She is married, mother of a lovely boy, and in her spare time, she listens to Bach and walks the dog.

---

See also the previous contributions to the inspiration-series by

• Anne
• Peter
• Kerstin
• Stefan
• Tommaso
• Chanda

and my related guest post at Asymptotia 'Sabine Hossenfelder: My Inspiration'.

---

TAGS: PHYSICS, PHYSICISTS

Gravity Defyer

Your days of shuffling down the corridor to the next seminar are over!

Here's what I found in the Skymall catalogue last week: The Gravity Defyer. Shoes with springs. Even if you're not, you'll walk young and dynamical. As you can see on the figure to the left, if you grin as stupidly as possible, you can jump up all the way up to the moon. "The energy reciprocating shock of the Gravity Defyer Shoe will spring you forward in life. The shoe is so much fun that the energy reciprocating shock of the Gravity Defying Shoe will actually give you the feeling of wanting to dance and be active. You might just find yourself joining a dance class soon! You will find a renewed enjoyment for walking places. You'll park farther away at the grocery store, shopping mall, and the office just to get extra time walking in your Gravity Defyer Shoes. "

Undoubtedly, you'll feel like it's the spring time of your life.

However, since this is a science blog, a word of caution is necessary. As a smart guy already pointed out, you should be aware that this ingenious invention doesn't actually defy gravity. I.e. you'll have to wait for anti-gravitation to be discovered to actually levitate. The only thing that's really innovative about this product is its name. Besides this, I want to complain that I couldn't find any Gravity Defying high heels (working on my minority issues). What is there left to say except:


If you liked this post, you might also like: Priceless and the Albert Einstein Action Figure.

---

TAGS: GRAVITY, GRAVITY DEFYER

Total Eclipse of the Moon

Right now, at 20:18:11 UT to be precise, the Moon is entering the so-called penumbral region of the shadow cone the Earth is casting into space - that's the beginning of a total eclipse of the moon! Clifford has linked to some beautiful photos of the "Red Moon", as it is sometimes called because of the reddish glow caused by light scattered in the Earth's atmosphere that makes in the geometric cone of the shadow.

If you want to know if you can see it, depending on where you live, you can have a look at this map, provided by NASA's eclipse guru Fred Espenak:


(Source: NASA)

In the central, white zone, you can, in principle, see the whole eclipse. The outer lines mark the phase of the eclipse at moonrise (for the Americas) or moonset (for Asia and Australia). The labels P1, U1, U2, U3, U4, and P2 correspond to the different phases of the eclipse, the entering of the penumbra (P1) and the umbra (U1), the begin and end of the total eclipse (U2 and U3), and the leaving of the umbra (U4) and penumbra (P4). So, if you live on the east coast of the US, the beginning of the total eclipse is just at moonrise (U2).


(Source: NASA)

Most spectacular, of course, is the phase if total eclipse from 22:44:13 UT to 23:57:37 UT, with the moment of greatest eclipse at 23:20:56 UT.

Of course, a dense cover of clouds can spoil the show - that's what seems to happen here in Frankfurt am Main. For all of us who cannot see anything, either because of clouds, or because you are living in the "wrong" hemisphere, the German association of amateur astronomers has organised a

• live reporting

from a place in the Siebengebirge near Bonn. So far, they have more luck with the weather than I have. Let's hope that they, at least, will have clear skies tonight!

This and That

• Christine Dantas, who some of you will remember from her blog Background Independence, is back with a new blog called Theorema Egregium.



• The 7th edition of the blog carnival Philosophia Naturalis is out at Geekpoint, and as always it has a lot of interesting links. We are in with my post about The world's largest microscope.



• Things you only learn at this blog: the ASCII code for the degree-symbol is 176, here is with special dedication to Frank:
  
  
  °°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°
  
  
  You produce this thing by either typing &deg; or &#176; and I promise to use it from now on.



• The Canadian Association of Physicists has an annual Art of Physics Competition. The website is not worth checking out because it mostly consists of broken links, but the winner photo from 2003 is just great:
  
  

  [Photo Credits: David Elfstrom, 'Hand through flat soap bubble']

  
  



• Update: In case you didn't know, the International Polar Year begun yesterday. Interestingly, the Polar Year lasts two years.



• Have a nice day!

Status Report

My mum is really cute, I love her. Last week she wrote she has seen on TV that NYC has had some snow, and if we also have snow? This was probably the funniest email I've received this year. But interestingly, every week or so, someone asks this question. So. Here's the answer.

Folks. I live in C-A-N-A-D-A. That's the large thing between the USA and the North pole. If I'd mention it every time we have snow, this wouldn't be a science blog, but a snow blog. The people here don't know what to do with all that snow. Before I moved here, I never realized that it can become a problem if the stuff doesn't melt away. I mean, they push it to the sidewalks and into the backyards, but it just piles up. I have seen street signs vanishing in snow hills, no kidding.

Today, the radio announced actually 'snow' and not 'flurries'. This came together with the recommendation not to leave the house, a whole list of closures, and cancellations for events and meetings. Unfortunately, I had to leave the house again. (Well. I was out of Coke, so this was really an emergency.) I forgot to take a photo of the car before I had shoveled it free, just believe me it was covered by at least 20 cm of snow.

Yes, today is March 1st.

If that doesn't impress you, let me add: the car was covered with 20cm of snow - after it was parked in the lot for 1 hour.

Here are some photos taken in front of the groceries store. I know they won't win an award for photographic quality, but it's been something like -15 C, feels like -20 or such, and after 2 minutes my fingers were so numb I couldn't push the buttons any more. Not sure if it's obvious but the second photo shows a bench. A nice place to chill out.

While I was shoveling free my car, a jacket with a toque came by and said: Quite some snow, eh? I know, it's a cliche, but they really do use this 'eh' always and everywhere. I said: Name me one good reason to move from California to Canada! EH? This scared the guy away. But since I know my sarcasm sometimes comes out the wrong way: I just like to complain about the weather. I can't say I exactly know why I decided to move here, but I don't regret it. It's maybe the first time that I like to go to work, and that I don't feel completely misplaced. I didn't expect it to make such a big difference, but it does.

However. I've promised myself and my friends if I have my own institute, it will be on a sunny beach.

Yes, yes, I'm working on it...

Quantum Gravity in the Lab

On Tuesday, we had the first meeting of the discussion group on 'Quantum Gravity in the Lab' that I've set up here at PI. As I've mentioned earlier, I exported the topic to a blog on its own. This is a copy of the entry from the first meeting. Comments are off here, because I want to encourage you to leave comments over there.

I had the intention to briefly summarize all the good reasons for the discussion group, but obviously I forgot half of what I wanted to say. So, if you're reading this you definitely have an advantage.

The reason for me setting up the discussion group was that even for those who are smart enough not to work on it, quantum gravity is the holy grail of theoretical physics in the 21st century. And here we are, standing on the shoulders of giants, trying to make a step without falling down. Luckily, over the last decade, we were able to move the giants a bit, and it's become quite fashionable to work on not derived, but well motivated models that incorporate the one or the other feature of the pursued full theory: like a minimal length scale, extra dimensions, modified dispersion relations, decoherence in a Planck-scale foamy background etc.

However, when I read papers about phenomenological implications of quantum gravity, they most often start with sentences like 'the recently proposed model...' or, 'Recently, it has been shown...', and I'm wondering if there's a decay time for the word 'recently'. E.g. the idea of having the 'true' Planck scale around a TeV dates back about a decade; DSR in it's present version came up around 00/01; early ideas about curved momentum spaces, modified dispersion relations etc. date back far longer.

Yes, it's a new field. But there are more and more people working on it every year, and it's about time that we get an overview about who is doing what, where progress has been made, and what problems have been faced. Part of this discussion group's intention is to summarize these efforts and see how promising they are (though this is surely a subjective judgement that I don't remotely mean to make objective).

The other part of the reason for the meetings is that I, being a particle physicist, find myself a bit lost in the quantum gravity seminars. It is clear that most of these approaches are very strong on the theoretical side, but lack some application. And I repeatedly ask myself if one couldn't investigate this or that feature. So, I would really like to bridge the gap between theory and experiment, to hear your ideas - however weird they might be - how one could test quantum gravity. (On my desk, if possible.)

Roughly speaking, the discussion group is therefore the forum for you to ask all the really stupid questions, and to spit out all the half-cooked topics that you have in mind. I deliberately have not scheduled speakers for the whole term. I want to see what issues come up and be flexible to focus on those that attract the most interest.

In the first meeting, I want to outline what we're going to talk about. Not so much because I don't like vivid discussions, but mostly because I'm not a good philosopher. It's not only that I constantly mix up words that end on -ism, but I generally don't like to argue about words whose meaning hasn't been clarified. So, to begin with, we should try to figure out what we mean with 'quantum gravity' and it's 'phenomenology'.

To me quantum gravity is the try to resolve the apparent disagreement between general relativity and quantum field theory. I say 'apparent' because, well, I'm pretty sure nature knows how to deal with that, so there ought to be a solution to the problem. Since three out of the four interactions in the standard model are quantized, it's natural to expect that also the fourth one - gravity - has to be quantized. In the meaning that the metric is no longer a classical field.

However, I think one should keep in mind that we actually don't know whether gravity is quantized at all. That doesn't solve the problem how it goes along with quantum field theory, but it's nevertheless a possibility. In this case one has a semi-classical theory with an unquantized gravitational field. The question is then how quantum field theory couples to the classical field. This comes with all the issues about renormalization, the vacuum, and as Rafael points out one has to think about what happens to the quantum nature (determinism) of the theory. (This is a topic I've also scratched in the comments at CV here.) Yes, I'm not claiming I know how to deal with that, I just don't a priory see why this is a totally inconsistent try. I don't think anybody knows what happens to the gravitational field of a 'collapsing' wave-function, so there's definitely room to play around there. So, apart from the quantization of the metric, one has the question what happens to the quantization itself.

Further, if one thinks about quantum gravity as stuff that happens when the curvature gets strong, one also has to consider modifications of gravity itself. These might, or might not be motivated by a quantization approach. Issues like singularity avoidance, the cosmological constant, dark matter etc could fall in this range.

One way or the other, as the status is right know, if one starts attacking quantum gravity and wants to investigate phenomenological implications, one makes some more or less motivated approximations, and cooks up an effective model that one can use to make a prediction. I want to point out (if you've read my recent paper you know why) that besides making predictions for new experiments, one shouldn't forget to reproduce all the old and boring stuff in the standard model. You know. Like, apples falling to the ground, photon self-energy, nuclear decay. These things.

The important question is then, what information got lost in the intermediate steps from the 'full theory' to the prediction. That is, we have kind of an inverse problem. Given that we were lucky enough to actually measure something, what could we learn about the full theory? Therefore, questions we should ask about all of the proposed phenomenological approaches are

• How stringent is the top-down approach (derivation/motivation)?
• How good works the bottom-up connection (reproduces standard model)?
• Exactly what is predicted under which assumptions?
• What could be learned from the outcome of the experiment (positive as well as negative)?

Lee mentions that I'm being too strict and since everything is going so badly we should try something unusual and not set too many requirements to our models. Well, for one I don't think everything is going badly, but more importantly, I haven't set any requirements. These are just the points I think one should investigate about the presently discussed approaches. See, this is just great about being at PI. Here, it's me who's considered being too conservative.

This is obviously a completely biased summary of the meeting, and I've dropped every comment that I didn't like or didn't understand.

---

TAGS: PHYSICS, QUANTUM GRAVITY

Disneyverse

Last weekend, I was really fed up with snow and literally jumped on the next plane to somewhere. Somewhere turned out to be LA, and if I had looked at a calendar in advance, I probably wouldn't have chosen the week between President's day and the Oscars.

Anyway, my hotel reservations were messed up in every place that I had booked (even though I had already payed for), and after some random walk I ended up staying in a really weird place at the Ocean Front Walk in Venice Beach. The whole room was painted in dark blue, furniture all in chrome, and all from IKEA (with the tags still on). Even the bedsheets were IKEA (I have the same). There was no toilet paper, but a huge flat-screen on the wall. There was no heating, but a fridge large enough to store a whole cow. There was no hair dryer, but a high speed WLAN. There was no key, but a touch pad. I never saw anybody who worked at that place. I just called a number and the guy said: go to room 17, code is 1717 (I was very tempted to try next door with 1818).

I didn't do so very much that week, except maybe reading papers on the beach instead of my office, and scribbling on Starbucks napkins among palm tress instead of scribbling among toque-wearing maple-syrup addicts. Oh, yes, and I went to Disneyland. Here are some photos from an almost causally disconnected part of the multiverse

Disney's World never worked for me. It's too illogical, there are too many open ends that don't meet (and Donald's eternal struggles are too frustrating). But it's just amazing how much attention they have payed to the smallest details. For some hours, it's a very nice fantasy world. But it's a bubble. And when you ask what keeps this world together, you'll notice the laws of this universe don't allow it to exist for very long. Maybe a Harry Potter World would work better. I'm not a large Potter fan, but one has to give it to Rowling that she's payed a lot of attention to keeping her imaginative world consistent. At least to some degree.

Regarding virtual realities and parallel worlds you might also like to read Terence Tao's post about Quantum Mechanics and TombRaider. Regarding leaving towns and bubbling landscapes, see also John Baez' review of Lee Smolin's book.

I had been hoping when I come back all the snow would have been gone, but unfortunately Toronto is still covered with white stuff. It's gotten considerably warmer though, the temperature rose to a stunning -2 C, and I feel almost like spring time.

---

TAGS: DISNEYWORLD, MULTIVERSE