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.
Tuesday, November 29, 2011
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)
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 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:
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
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
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.
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 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.
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]nordita.org
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]nordita.org
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
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.
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
arXiv:1109.4947
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.
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 Sciflies.org, 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.
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 Sciflies.org, 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
Interna
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?
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?
Friday, October 21, 2011
Interna
After the previous posts were somewhat heavy in content, for relaxation let me just show you some photos from a recent weekend excursion.
[Click to badastronate]
My month back at work is almost over, and we'll be commuting back to Germany in the coming days so Superdaddy can reappear in his office chair.
[Click to badastronate]
My month back at work is almost over, and we'll be commuting back to Germany in the coming days so Superdaddy can reappear in his office chair.
Monday, October 17, 2011
Super Extra Loop Quantum Gravity
In the summer, I noted a recent paper that scored remarkably low on the bullshit index:
But what is the paper actually about? It is an attempt to make contact between Loop Quantum Gravity (LQG) and Superstring Theory (ST). Both are approaches to a quantization of gravity, one of the big open problems in theoretical physics. LQG directly attacks the problem by a careful selection of variables and quantization procedure. String theory does not only aim at quantizing gravity, but at the same time at unifying also the other 3 interactions of the standard model by taking as fundamental the strings that give it its name. If quantizing gravity and unifying the standard model interactions are actually related problems, then string theorists are wise to attack them together. Yet, we don't know if they are related. In any case, it has turned out that gravity is necessarily contained in ST.
Both theories still struggle to reproduce general relativity and/or the standard model, and to make contact to phenomenology, though for very different reasons. This begs the question how the theories compare to each other, whether they give the same results for selected problems. Unfortunately, so far this has not been possible to answer because LQG has been developed for a 3+1 dimensional space-time, while ST famously or infamously, depending on your perspective, necessitates 6 additional dimensions that then have to be compactified. ST is also, as the name says, supersymmetric. It should be noted that these both features, supersymmetry and extra dimensions, are not optional but mandatory for ST to make sense.
I've always wondered why one hasn't extended LQG to higher dimensions since the idea of extra dimensions is appealing and somebody in the field who should have known better once told me it would be straight forward to do. It is however not so because one of the variables (a certain SU(2) Yang-Mills connection) used in the quantization procedure relies on a property (the equivalence of the fundamental and adjoint representations of SU(2)) that is fulfilled only in 3 spatial dimensions. So it took many years and two brilliant young students, Norbert Bodendorfer and Andreas Thurn, to come up with a variable that could be used in an arbitrary number of dimensions and to work through the maths which, as you can imagine, didn't get easier. It required to work around the difficulty that SO(1,D) is not compact and digging out a technique for gauge unfixing, a procedure that I had never heard of before.
Compared to the difficulty of adding dimensions, going supersymmetric can be done by simply generalizing the appropriate matter content which is contained in the supergravity actions, and constructing a supersymmetry constraint operator.
Taken together, this in principle allows one to compare the super extra loop quantized gravity to string theory, to which supergravity is a low energy approximation, though concrete calculations have yet to follow. One of the tasks on the to-do list the entropy of extremal supersymmetric black holes to see if LQG reproduces the ST results. (Or if not, which might be even more interesting.) Since LQG is a manifestly non perturbative approach, this relation to string theory might also help filling in some blanks in the AdS/CFT correspondence in areas where neither side of the duality is weakly coupled.
- Towards Loop Quantum Supergravity (LQSG)
Norbert Bodendorfer, Thomas Thiemann, Andreas Thurn
Bullshit Index : 0.08
Your text shows no or marginal indications of 'bullshit'-English.
But what is the paper actually about? It is an attempt to make contact between Loop Quantum Gravity (LQG) and Superstring Theory (ST). Both are approaches to a quantization of gravity, one of the big open problems in theoretical physics. LQG directly attacks the problem by a careful selection of variables and quantization procedure. String theory does not only aim at quantizing gravity, but at the same time at unifying also the other 3 interactions of the standard model by taking as fundamental the strings that give it its name. If quantizing gravity and unifying the standard model interactions are actually related problems, then string theorists are wise to attack them together. Yet, we don't know if they are related. In any case, it has turned out that gravity is necessarily contained in ST.
Both theories still struggle to reproduce general relativity and/or the standard model, and to make contact to phenomenology, though for very different reasons. This begs the question how the theories compare to each other, whether they give the same results for selected problems. Unfortunately, so far this has not been possible to answer because LQG has been developed for a 3+1 dimensional space-time, while ST famously or infamously, depending on your perspective, necessitates 6 additional dimensions that then have to be compactified. ST is also, as the name says, supersymmetric. It should be noted that these both features, supersymmetry and extra dimensions, are not optional but mandatory for ST to make sense.
I've always wondered why one hasn't extended LQG to higher dimensions since the idea of extra dimensions is appealing and somebody in the field who should have known better once told me it would be straight forward to do. It is however not so because one of the variables (a certain SU(2) Yang-Mills connection) used in the quantization procedure relies on a property (the equivalence of the fundamental and adjoint representations of SU(2)) that is fulfilled only in 3 spatial dimensions. So it took many years and two brilliant young students, Norbert Bodendorfer and Andreas Thurn, to come up with a variable that could be used in an arbitrary number of dimensions and to work through the maths which, as you can imagine, didn't get easier. It required to work around the difficulty that SO(1,D) is not compact and digging out a technique for gauge unfixing, a procedure that I had never heard of before.
Compared to the difficulty of adding dimensions, going supersymmetric can be done by simply generalizing the appropriate matter content which is contained in the supergravity actions, and constructing a supersymmetry constraint operator.
Taken together, this in principle allows one to compare the super extra loop quantized gravity to string theory, to which supergravity is a low energy approximation, though concrete calculations have yet to follow. One of the tasks on the to-do list the entropy of extremal supersymmetric black holes to see if LQG reproduces the ST results. (Or if not, which might be even more interesting.) Since LQG is a manifestly non perturbative approach, this relation to string theory might also help filling in some blanks in the AdS/CFT correspondence in areas where neither side of the duality is weakly coupled.
Friday, October 14, 2011
AdS/CFT confronts data
One of the most persistent and contagious side-effects of string theory has been the conjectured AdS/CFT correspondence (that we previously discussed here, here and here). The briefest of all brief summaries is that it is a duality that allows to swap the strong coupling limit of a conformal field theory (CFT) with (super)gravity in a higher dimensional Anti-de-Sitter (AdS) space. Since computation at strong coupling is difficult, at the very least this is a useful computational tool. It has been applied to some condensed matter systems and also to heavy ion physics, where one wants to know the properties of the quark gluon plama. Now the theory that one has to deal with in heavy ion collisions is QCD, which is neither supersymmetric nor conformal, but there have been some arguments for why it should be approximately okay.
The great thing about the application of AdS/CFT to heavy ion physics is that it made predictions for the LHC's heavy ion runs that are now being tested. One piece of data that is presently coming in is the distribution of jets in heavy ion collisions, but first some terminology.
A heavy ion is an atom with a high atomic number stripped of all electrons; typically one uses lead or gold. Compared to a proton, a heavy ion is a large clump of bound nucleons (neutrons and protons) that are accelerated and brought to collision. They may collide head-on or only peripherally, quantified in a number called "centrality." When the ions collide, they temporarily form a hot, dense soup of quarks and gluons called the "quark gluon plasma." This plasma rapidly expands and cools and the quarks and gluons form hadrons again (in a process called "hadronization" or also "fragmentation"), that are then detected. The temperature of the plasma depends on the energy of the colliding ions that is provided by the accelerator. At RHIC the temperature is about 350 MeV, in the LHC's heavy ion program it is about 500 MeV. The task of heavy ion physicists is to extract information about matter at nuclear densities and such high temperatures from the detected collision products.
A (di) jet is two back-to-back correlated showers of particles that are a typical signature in perturbative QCD. It is created if a pair of outgoing partons (quarks or gluons) hadronizes and produces a bunch of particles that then hit the detector. Since QCD is confined, the primary, colored, particles never reach the detector. In contrast to proton-proton collisions, in heavy ion collisions the partons have to first go through the quark gluon plasma before they can make a jet. Thus, the distribution of momenta of the observed jets depends on the properties of the plasma, in particular the energy loss that the partons undergo.
Different models predict different energy loss and dependence of that energy loss on the temperature of the medium. Jets are a QCD feature at weak coupling and strictly speaking in the strong coupling limit that AdS/CFT describes there are no jets at all. What one can however do is to use a hybrid model in which one just extracts the energy loss in the plasma from the conformal theory. This energy loss scales with L3 T4, where L is the length that the partons travel through the medium and T is the temperature. All other models for the energy loss scale with smaller powers of the temperature.
Heavy ion physicists like to encode observables into how different they are from the corresponding observables for collisions of the ion's constituents. The "nuclear suppression factor," denoted RAA, plotted in Thorsten Renk's figure below (Slide 17 of this talk), is basically the ratio of the cross-section for jets in lead-lead over the same quantity for proton-proton (normalized to the number of nucleons) and it's depicted as a function of the average transverse momentum (pT) of the jets. The black dots are the ALICE data, the solid lines are fits from various models. The orange line at the bottom is AdS/CFT.
[Picture credit: Thorsten Renk, Slide 17 of this presentention]
As the saying goes, a picture speaks a thousand words, but since links and image sources have a tendency to deteriorate over time, let me spell it out for you: The AdS/CFT scaling does not agree with the data at all.
A readjustment of parameters might move the total curve up or down, but the slope would still be off. Another problem with the AdS/CFT model is that the model parameters needed to fit the RHIC data are very different from the ones needed for the LHC. The model that does best is Yet another Jet Energy-loss Model (YaJEM) that works with in medium showers (I know nothing about that code). It is described in some detail in this paper. It doesn't only fit well with the observed scaling, it also does not require a large readjustment of parameters from RHIC to LHC.
Of course there's always caveats to a conclusion. One might criticize for example the way that AdS/CFT has been implemented into the code. But the scaling with temperature is such a general property that I don't think nagging at the details will be of much use here. Then one may want to point out that the duality is good actually only in the large N limit and N=3 isn't so large after all. And that is right, so maybe one would have to take correction terms more seriously. But that would then require calculating string contributions and one loses the computational advantage that AdS/CFT seemed to bring.
Some more details on the above figure are in Thorsten Renk's proceedings from the Quark Matter 2011, on the arxiv under 1106.2392 [hep-ph].
Summary: I predict applications of the AdS/CFT duality to heavy ion physics is a rapidly cooling area.
The great thing about the application of AdS/CFT to heavy ion physics is that it made predictions for the LHC's heavy ion runs that are now being tested. One piece of data that is presently coming in is the distribution of jets in heavy ion collisions, but first some terminology.
A heavy ion is an atom with a high atomic number stripped of all electrons; typically one uses lead or gold. Compared to a proton, a heavy ion is a large clump of bound nucleons (neutrons and protons) that are accelerated and brought to collision. They may collide head-on or only peripherally, quantified in a number called "centrality." When the ions collide, they temporarily form a hot, dense soup of quarks and gluons called the "quark gluon plasma." This plasma rapidly expands and cools and the quarks and gluons form hadrons again (in a process called "hadronization" or also "fragmentation"), that are then detected. The temperature of the plasma depends on the energy of the colliding ions that is provided by the accelerator. At RHIC the temperature is about 350 MeV, in the LHC's heavy ion program it is about 500 MeV. The task of heavy ion physicists is to extract information about matter at nuclear densities and such high temperatures from the detected collision products.
A (di) jet is two back-to-back correlated showers of particles that are a typical signature in perturbative QCD. It is created if a pair of outgoing partons (quarks or gluons) hadronizes and produces a bunch of particles that then hit the detector. Since QCD is confined, the primary, colored, particles never reach the detector. In contrast to proton-proton collisions, in heavy ion collisions the partons have to first go through the quark gluon plasma before they can make a jet. Thus, the distribution of momenta of the observed jets depends on the properties of the plasma, in particular the energy loss that the partons undergo.
Different models predict different energy loss and dependence of that energy loss on the temperature of the medium. Jets are a QCD feature at weak coupling and strictly speaking in the strong coupling limit that AdS/CFT describes there are no jets at all. What one can however do is to use a hybrid model in which one just extracts the energy loss in the plasma from the conformal theory. This energy loss scales with L3 T4, where L is the length that the partons travel through the medium and T is the temperature. All other models for the energy loss scale with smaller powers of the temperature.
Heavy ion physicists like to encode observables into how different they are from the corresponding observables for collisions of the ion's constituents. The "nuclear suppression factor," denoted RAA, plotted in Thorsten Renk's figure below (Slide 17 of this talk), is basically the ratio of the cross-section for jets in lead-lead over the same quantity for proton-proton (normalized to the number of nucleons) and it's depicted as a function of the average transverse momentum (pT) of the jets. The black dots are the ALICE data, the solid lines are fits from various models. The orange line at the bottom is AdS/CFT.
[Picture credit: Thorsten Renk, Slide 17 of this presentention]
As the saying goes, a picture speaks a thousand words, but since links and image sources have a tendency to deteriorate over time, let me spell it out for you: The AdS/CFT scaling does not agree with the data at all.
A readjustment of parameters might move the total curve up or down, but the slope would still be off. Another problem with the AdS/CFT model is that the model parameters needed to fit the RHIC data are very different from the ones needed for the LHC. The model that does best is Yet another Jet Energy-loss Model (YaJEM) that works with in medium showers (I know nothing about that code). It is described in some detail in this paper. It doesn't only fit well with the observed scaling, it also does not require a large readjustment of parameters from RHIC to LHC.
Of course there's always caveats to a conclusion. One might criticize for example the way that AdS/CFT has been implemented into the code. But the scaling with temperature is such a general property that I don't think nagging at the details will be of much use here. Then one may want to point out that the duality is good actually only in the large N limit and N=3 isn't so large after all. And that is right, so maybe one would have to take correction terms more seriously. But that would then require calculating string contributions and one loses the computational advantage that AdS/CFT seemed to bring.
Some more details on the above figure are in Thorsten Renk's proceedings from the Quark Matter 2011, on the arxiv under 1106.2392 [hep-ph].
Summary: I predict applications of the AdS/CFT duality to heavy ion physics is a rapidly cooling area.
Wednesday, October 12, 2011
New constraints on energy-dependent speed of light from gamma ray bursts
Two weeks ago, an arXiv preprint came out with a new analysis of the highest energetic gamma ray bursts (GRBs) observed with the Fermi telescope. This paper put forward a bound on an energy-dependent speed of light that is an improvement of 3 orders of magnitude over existing bounds. This rules out a class of models for Planck-scale effects. If you know the background, just scroll down to "News" to read what's new. If you need a summary of why this is interesting and links to earlier discussions, you'll find that in the "Avant-propos".
Avant-propos
Deviations from Lorentz-invariance are the best studied case of physics at the Planck scale. Such deviations can have two different expressions: Either an explicit breaking of Lorentz-invariance that introduces a preferred restframe, or a so-called deformation that changes Lorentz-transformations at high energies without introducing a preferred restframe.
Such new effects are parameterized by a mass scale that, if it is a quantum gravitational effect, one would expect to be close by the Planck-mass. Extensions of the standard model that explicitly break Lorentz-invariance are very strongly constrained already, to 9 orders of magnitude above the Planck mass. Such constraints are derived by looking for effects on particle physics that are a consequence of higher order operators in the standard model.
Deformations of special relativity (DSR) evade that type of constraints, basically because there is no agreed upon effective limit from which one could actually read off higher order operators and calculate such effects. It is also difficult, if not impossible, to make sense of DSR in position space without ruining locality and these models have so-far unresolved issues with multi-particle states. So, as you can guess, there's some controversy among the theorists about whether DSR is a viable model for quantum gravitational effects. (See also this earlier post.) But that's arguments from theory, so let's have a look at the data.
Some models of DSR feature an energy-dependent speed of light. That means that photons travel with different speeds depending on their energy. This effect is very small. In the best case, it scales with the photon's energy over the Planck mass which, even for photons in the GeV range, is a a factor 10-19. But the total time difference between photons of different energies can add up if the photons travel over a long distance. Thus the idea is to look at photons with high energies coming to us from far away, such as those emitted from GRBs. It turns out that in this case, with distances of some Gpc and energies at some GeV, an energy-dependent speed of light can become observable.
There's two things one should add here. First, not all cases of DSR do actually have an energy-dependent speed of light. Second, not in all cases does it scale the same way. That is, the above discussed case is the most optimistic one when it comes to phenomenology, the one with the most striking effect. For that reason, it's also the case that has been talked about the most.
There had previously been claims from analysis of GRB data that the scale at which the effect becomes important had been constrained up to about 100 times the Planck mass. This would have been a strong indication that the effect, if it is a quantum gravitational effect, is not there at all, ruling out a large class of DSR models. However, we discussed here why that claim was on shaky ground, and indeed it didn't make it through peer review. The presently best limit from GRBs is just about at the Planck scale.
News
Now, three researchers from Michigan Technological University, have put forward a new analysis that has appeared on the arxiv:
Previous analysis had studied the difference in arrival times between the low and high energetic photons. In the new study, the authors have exclusively looked at the high energetic photons, noting that the average difference in energies between photons in the GeV range is about the same as that between photons in the GeV and the MeV range, and for the delay it's only the difference that matters. Looking at the GeV range has the added benefit that there is basically no background.
For their analysis, they have selected a subsample of the total of 600 or so GRBs that Fermi has detected so far. From all these events, they have looked only at those who have numerous photons in the GeV range to begin with. In the end they consider only 4 GRBs (080916C, 090510A, 090902B, and 090926A). From the paper, it does not really become clear how these were selected, as this paper reports at least 19 events with statistically significant contributions in the GeV range. One of the authors of the paper, Robert Nemiroff, explained upon my inquiry that they selected the 4 GRBs with the best high energy data, numerous particles that have been identified as photons with high confidence.
The authors then use a new kind of statistical analysis to extract information from the spectrum, even though we know little to nothing about the emission spectrum of the GRBs. For their analysis, they study exclusively the timing of the high energetic photons' arrival. Just by looking at the Figure 2 from their paper you can see that on occasion two or three photons of different energies arrive almost simultaneously (up to some measurement uncertainty). They study two methods of extracting a bunch from the data and then quantify its reliability by testing it against a Monte Carlo simulation. If one assumes a uniform distribution and just sprinkles photons in the time interval of the burst, a bunch is very unlikely to happen by coincidence. Thus, one concludes with some certainty that this 'bunching' of photons must have been present already at the source and was maintained during propagation. An energy-dependent dispersion would tend to wash out such correlations as it would increase the time difference between photons with different energies. Then, from the total time of the bunch of photons and its variability in energy, one can derive constraints on the dispersion that this bunch can have undergone.
Clearly, what one would actually want to do is a Monte Carlo analysis with and without the dispersion and see which one fits the data better. Yet, one cannot do that because one doesn't know the emission spectrum of the burst. Instead, the procedure the authors use just aims at extracting a likely time variability. In that way, they can then identify in particular one very short substructure in GRB 090510A that in addition also has a large spread in energy. From this (large energy difference but small time difference) they then extract a bound on the dispersion and, assuming a first order effect, a bound on the scale of possible quantum gravitational effects that is larger than 3060 times the Planck scale. If this result holds up, this is an improvement by 3 orders of magnitude over earlier bounds!
Comments
The central question is however what is the confidence level for this statement. The bunching they have looked at in each GRB is a 3σ effect, i.e. it would appear coincidentally only in one out of 370 cases that they generated per Monte Carlo trials: "Statistically significant bunchiness was declared when the detected counts... occurred in less than one in 370 equivalent Monte Carlo trials." Yet they are extracting their strong bound from one dataset (GRB) of a (not randomly chosen) subsample of all recorded data. But the probability to expect such a short bunch just by pure coincidence in one out of 20 cases is higher than the probability to find it coincidentally in just one. Don't misunderstand me, it might very well be that the short-timed bunch in GRB 090510A has a probability of less than one in 370 to appear just coincidentally in the data we have so far, I just don't see how that follows from the analysis that is in the paper.
To see my problem, consider that (and I am not saying this has anything to do with reality) the GRB had a completely uniform emission in some time window and then suddenly stops. The only two parameters are the time window and the total number of photons detected. In the low energy range, we detect a lot of photons and the probability that the variation we see happened just by chance even though the emission was uniform is basically zero. In the high energy range we detect sometimes a handful, sometimes 20 or so photons. If you assume a uniform emission, the photons we measure will simply by coincidence sometimes come in a bunch if you measure enough GRBs, dispersion or not. That is, the significance of one bunch in one GRB depends on the total size of the sample, which is not the same significance that the authors have referred to. (You might want to correlate the spectrum at high energies with the better statistic at low energies, but that is not what has been done in this study.)
The significance that is referred to in the paper is how well their method extracts a bunch from the high energy spectrum. The significance I am asking for is a different one, namely what is the confidence by which a detected bunch does actually tell us something about the spectrum of the burst.
Summary
The new paper suggests an interesting new method to extract information about the time variability of the GRB in the GeV range by estimating the probability that the observed bunched arrivals of photons might have occurred just by chance even though there is dispersion. That allows to bound a possible Planck scale effect very tightly. Since I have written some papers arguing from theoretical grounds that there should be no Planck scale effect in the GRB spectra, I would be pleased to see an observational confirmation of my argument. Unfortunately, the statistical relevance of this new claim is not entirely clear to me. The relevance that is referred to in the paper I am not sure how to translate into the relevance of the bound. Robert Nemiroff has shown infinite patience to explain the reasoning to me, but I still don't understand it. Let's see what the published version of the paper says.
Avant-propos
Deviations from Lorentz-invariance are the best studied case of physics at the Planck scale. Such deviations can have two different expressions: Either an explicit breaking of Lorentz-invariance that introduces a preferred restframe, or a so-called deformation that changes Lorentz-transformations at high energies without introducing a preferred restframe.
Such new effects are parameterized by a mass scale that, if it is a quantum gravitational effect, one would expect to be close by the Planck-mass. Extensions of the standard model that explicitly break Lorentz-invariance are very strongly constrained already, to 9 orders of magnitude above the Planck mass. Such constraints are derived by looking for effects on particle physics that are a consequence of higher order operators in the standard model.
Deformations of special relativity (DSR) evade that type of constraints, basically because there is no agreed upon effective limit from which one could actually read off higher order operators and calculate such effects. It is also difficult, if not impossible, to make sense of DSR in position space without ruining locality and these models have so-far unresolved issues with multi-particle states. So, as you can guess, there's some controversy among the theorists about whether DSR is a viable model for quantum gravitational effects. (See also this earlier post.) But that's arguments from theory, so let's have a look at the data.
Some models of DSR feature an energy-dependent speed of light. That means that photons travel with different speeds depending on their energy. This effect is very small. In the best case, it scales with the photon's energy over the Planck mass which, even for photons in the GeV range, is a a factor 10-19. But the total time difference between photons of different energies can add up if the photons travel over a long distance. Thus the idea is to look at photons with high energies coming to us from far away, such as those emitted from GRBs. It turns out that in this case, with distances of some Gpc and energies at some GeV, an energy-dependent speed of light can become observable.
There's two things one should add here. First, not all cases of DSR do actually have an energy-dependent speed of light. Second, not in all cases does it scale the same way. That is, the above discussed case is the most optimistic one when it comes to phenomenology, the one with the most striking effect. For that reason, it's also the case that has been talked about the most.
There had previously been claims from analysis of GRB data that the scale at which the effect becomes important had been constrained up to about 100 times the Planck mass. This would have been a strong indication that the effect, if it is a quantum gravitational effect, is not there at all, ruling out a large class of DSR models. However, we discussed here why that claim was on shaky ground, and indeed it didn't make it through peer review. The presently best limit from GRBs is just about at the Planck scale.
News
Now, three researchers from Michigan Technological University, have put forward a new analysis that has appeared on the arxiv:
- Limiting properties of light and the universe with high energy photons from Fermi-detected Gamma Ray Bursts
By Robert J. Nemiroff, Justin Holmes, Ryan Connolly
arXiv:1109.5191 [astro-ph.CO]
Previous analysis had studied the difference in arrival times between the low and high energetic photons. In the new study, the authors have exclusively looked at the high energetic photons, noting that the average difference in energies between photons in the GeV range is about the same as that between photons in the GeV and the MeV range, and for the delay it's only the difference that matters. Looking at the GeV range has the added benefit that there is basically no background.
For their analysis, they have selected a subsample of the total of 600 or so GRBs that Fermi has detected so far. From all these events, they have looked only at those who have numerous photons in the GeV range to begin with. In the end they consider only 4 GRBs (080916C, 090510A, 090902B, and 090926A). From the paper, it does not really become clear how these were selected, as this paper reports at least 19 events with statistically significant contributions in the GeV range. One of the authors of the paper, Robert Nemiroff, explained upon my inquiry that they selected the 4 GRBs with the best high energy data, numerous particles that have been identified as photons with high confidence.
The authors then use a new kind of statistical analysis to extract information from the spectrum, even though we know little to nothing about the emission spectrum of the GRBs. For their analysis, they study exclusively the timing of the high energetic photons' arrival. Just by looking at the Figure 2 from their paper you can see that on occasion two or three photons of different energies arrive almost simultaneously (up to some measurement uncertainty). They study two methods of extracting a bunch from the data and then quantify its reliability by testing it against a Monte Carlo simulation. If one assumes a uniform distribution and just sprinkles photons in the time interval of the burst, a bunch is very unlikely to happen by coincidence. Thus, one concludes with some certainty that this 'bunching' of photons must have been present already at the source and was maintained during propagation. An energy-dependent dispersion would tend to wash out such correlations as it would increase the time difference between photons with different energies. Then, from the total time of the bunch of photons and its variability in energy, one can derive constraints on the dispersion that this bunch can have undergone.
Clearly, what one would actually want to do is a Monte Carlo analysis with and without the dispersion and see which one fits the data better. Yet, one cannot do that because one doesn't know the emission spectrum of the burst. Instead, the procedure the authors use just aims at extracting a likely time variability. In that way, they can then identify in particular one very short substructure in GRB 090510A that in addition also has a large spread in energy. From this (large energy difference but small time difference) they then extract a bound on the dispersion and, assuming a first order effect, a bound on the scale of possible quantum gravitational effects that is larger than 3060 times the Planck scale. If this result holds up, this is an improvement by 3 orders of magnitude over earlier bounds!
Comments
The central question is however what is the confidence level for this statement. The bunching they have looked at in each GRB is a 3σ effect, i.e. it would appear coincidentally only in one out of 370 cases that they generated per Monte Carlo trials: "Statistically significant bunchiness was declared when the detected counts... occurred in less than one in 370 equivalent Monte Carlo trials." Yet they are extracting their strong bound from one dataset (GRB) of a (not randomly chosen) subsample of all recorded data. But the probability to expect such a short bunch just by pure coincidence in one out of 20 cases is higher than the probability to find it coincidentally in just one. Don't misunderstand me, it might very well be that the short-timed bunch in GRB 090510A has a probability of less than one in 370 to appear just coincidentally in the data we have so far, I just don't see how that follows from the analysis that is in the paper.
To see my problem, consider that (and I am not saying this has anything to do with reality) the GRB had a completely uniform emission in some time window and then suddenly stops. The only two parameters are the time window and the total number of photons detected. In the low energy range, we detect a lot of photons and the probability that the variation we see happened just by chance even though the emission was uniform is basically zero. In the high energy range we detect sometimes a handful, sometimes 20 or so photons. If you assume a uniform emission, the photons we measure will simply by coincidence sometimes come in a bunch if you measure enough GRBs, dispersion or not. That is, the significance of one bunch in one GRB depends on the total size of the sample, which is not the same significance that the authors have referred to. (You might want to correlate the spectrum at high energies with the better statistic at low energies, but that is not what has been done in this study.)
The significance that is referred to in the paper is how well their method extracts a bunch from the high energy spectrum. The significance I am asking for is a different one, namely what is the confidence by which a detected bunch does actually tell us something about the spectrum of the burst.
Summary
The new paper suggests an interesting new method to extract information about the time variability of the GRB in the GeV range by estimating the probability that the observed bunched arrivals of photons might have occurred just by chance even though there is dispersion. That allows to bound a possible Planck scale effect very tightly. Since I have written some papers arguing from theoretical grounds that there should be no Planck scale effect in the GRB spectra, I would be pleased to see an observational confirmation of my argument. Unfortunately, the statistical relevance of this new claim is not entirely clear to me. The relevance that is referred to in the paper I am not sure how to translate into the relevance of the bound. Robert Nemiroff has shown infinite patience to explain the reasoning to me, but I still don't understand it. Let's see what the published version of the paper says.
Wednesday, October 05, 2011
Away note
I'll be away the rest of the week for a brief trip to Jyväskylä, Finland. I'm also quite busy next week, so don't expect to hear much from me.
For your distraction, here's some things that I've come across that you might enjoy:
For your distraction, here's some things that I've come across that you might enjoy:
- Correlations between hobbies and impact factors of scientists (via Garrett). It seems I should do more painting again...
- If life gives you lemons, well, you know. If life gives you ants, give them food colors.
- Money as an incentive doesn't work well for creative labor.
- I came across an amusing footnote in a 1994 paper that quotes J.A. Wheeler in private correspondence
[I recall] the well-known statement of Rutherford, "When a student of mine uses the word "universe", I tell him it is time for him to leave." But maybe that's why so many of us live in America!
Those where the days. - Random advice: If you plan on uploading a paper, make sure you've removed all comments...
- And a movie wanting to communicate that scientists are human beings, if you had any doubts.
Sunday, October 02, 2011
FAZ: Interview with German member of OPERA collaboration
The German newspaper Frankfurter Allgemeine Zeitung (FAZ) has an interesting interview with Caren Hagner, from the University of Hamburg. Hagner is member of the OPERA collaboration and talked to the journalist Manfred Lindinger. The interview is in German and I thought most of you would probably miss it, so here's some excerpts (translation mine):
Hagner also says that the statistical analysis (matching the proton spectrum with that of the neutrinos) should have been redone by different techniques and that this is currently under way. She further points out that the results are only from one of two detection methods that OPERA has, the scintillation-tracker. Another detector, the spectrometer, should yield an independent measurement that could be compared to the first, but that would take about 2 months.
The final question is also worth quoting:
Frau Hagner, you are leader of the German group of the OPERA experiment. But one searches in vain for your name on the preprint.
I and a dozen of colleagues did not sign the preprint. I have no reservations about the experiment. I just think it was premature to go public with the results for such an unusual effect like faster than light travel. One should have done more tests. But then the publication would have taken at least 2 months longer. I and other colleagues from the OPERA collaboration wanted these tests to be done.
What tests?
First, a second independent analysis. In particle physics, if one believes to have discovered a new particle or effect, then in general there is not only one group analyzing the data but several. And if all get the same result then one can be convinced it is right. That has not been the case with OPERA.
Why?
Because there hasn't been time. For an effect like faster than light travel the analysis should certainly be controlled. Maybe there is a bug in the program [...] The majority of the collaboration preferred a quick publication.
Hagner also says that the statistical analysis (matching the proton spectrum with that of the neutrinos) should have been redone by different techniques and that this is currently under way. She further points out that the results are only from one of two detection methods that OPERA has, the scintillation-tracker. Another detector, the spectrometer, should yield an independent measurement that could be compared to the first, but that would take about 2 months.
The final question is also worth quoting:
[If true], might satellite navitation in the future be based on neutrino rays rather than light?
Yes, maybe. But then our GPS devices would weigh some thousand tons.
Friday, September 30, 2011
Interna
Lara and Gloria are now 9 months old, and it's time again for our monthly baby update. The girls are now both crawling well. Lara has learned to sit up on her own and Gloria knows how to pull herself up and stand on her feet. She's been doing that since 2 weeks already, but only now has she learned how to get back down in any other way than just letting go and falling backwards on her head. There's no day the babies don't get new scratches or bruises and they are relentlessly curious. The other day they escaped from the baby-safe part of the room and happily chewed on our passports.
When they are not sleeping or crying, they are babbling most of the time. For a few days in a row they pick a favorite syllable that they then repeat endlessly. Presently, Gloria is commenting everything with na-na-na, and Lara is practicing dadn-dadn. I've speculated she's echoing Stefan's "Was mascht Du dadn?" (What are you doing there? Saarland-style). On Monday we took them to the institute and they were duly impressed by the guy next door drawing Feynman-diagrams on the whiteboard, though more interesting still they found all the cables under my desk together with the occasional woodlouse that we evidently host down there.
I always thought babies typically swallow or choke on everything small enough to fit into their mouth. It turns out though the very little ones put things in their mouth but don't swallow. In fact, at this point ours still refuse to eat anything that's not smoothly mashed. They'll just push it around in their mouth for a little and then spit out. (It's called the "gag reflex" and should vanish by 7-9 months. You better not leave your baby alone with the combustion engine anyway.)
Neither Lara nor Gloria have teeth yet. That has not deterred the Swedish health authorities from assigning us dentists' appointment. It's not like they ask you to come, no, they just send a letter with a time, date, and location you have to appear. We actually missed the first two appointments. I then called them and tried to convey the information that the girls don't even have teeth for the dentist to look at, but to no avail. I'm picturing a long corridor with offices where Swedish doctors sit and cross out names of patients that didn't show up for their appointments, or belatedly notice the body part they wanted to examine is missing. But at least we know where our taxes are going. (The same health authorities that require amputees to prove every other year that the missing part hasn't regrown. Still better than no health insurance...)
Stefan was sent a list of gadgets the modern father needs to have, for example the full color, high-def, video monitoring system, that allows you to check on your babies by Skype, or a cry analyzer. But the gadget that I would really like to have is a diaper with an integrated microchip that sends a note to my BlackBerry when the diaper is full, and a number attached to it. It's somewhat degrading to having to push my nose onto baby-butts in order to examine the matter, and Stefan's nose evidently isn't up to the task. The German comedian Michael Mittermeier aptly referred to the nose-on-butt procedure as "the shit-check." Which reminds me, I should really write the report on that paper now...
When they are not sleeping or crying, they are babbling most of the time. For a few days in a row they pick a favorite syllable that they then repeat endlessly. Presently, Gloria is commenting everything with na-na-na, and Lara is practicing dadn-dadn. I've speculated she's echoing Stefan's "Was mascht Du dadn?" (What are you doing there? Saarland-style). On Monday we took them to the institute and they were duly impressed by the guy next door drawing Feynman-diagrams on the whiteboard, though more interesting still they found all the cables under my desk together with the occasional woodlouse that we evidently host down there.
I always thought babies typically swallow or choke on everything small enough to fit into their mouth. It turns out though the very little ones put things in their mouth but don't swallow. In fact, at this point ours still refuse to eat anything that's not smoothly mashed. They'll just push it around in their mouth for a little and then spit out. (It's called the "gag reflex" and should vanish by 7-9 months. You better not leave your baby alone with the combustion engine anyway.)
Neither Lara nor Gloria have teeth yet. That has not deterred the Swedish health authorities from assigning us dentists' appointment. It's not like they ask you to come, no, they just send a letter with a time, date, and location you have to appear. We actually missed the first two appointments. I then called them and tried to convey the information that the girls don't even have teeth for the dentist to look at, but to no avail. I'm picturing a long corridor with offices where Swedish doctors sit and cross out names of patients that didn't show up for their appointments, or belatedly notice the body part they wanted to examine is missing. But at least we know where our taxes are going. (The same health authorities that require amputees to prove every other year that the missing part hasn't regrown. Still better than no health insurance...)
Stefan was sent a list of gadgets the modern father needs to have, for example the full color, high-def, video monitoring system, that allows you to check on your babies by Skype, or a cry analyzer. But the gadget that I would really like to have is a diaper with an integrated microchip that sends a note to my BlackBerry when the diaper is full, and a number attached to it. It's somewhat degrading to having to push my nose onto baby-butts in order to examine the matter, and Stefan's nose evidently isn't up to the task. The German comedian Michael Mittermeier aptly referred to the nose-on-butt procedure as "the shit-check." Which reminds me, I should really write the report on that paper now...
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