Saturday, December 23, 2006

Home for Christmas

I was supposed to help my mother decorate the Christmas tree, but I sneaked away to tell you something about the Christmas tradition in Germany (version: how I know it).

Unlike in North America, in Germany Christmas is not celebrated on Dec. 25th, but on the evening of Dec. 24th. The German word 'Weihnacht' is better translated as 'Holy Night'. The official holidays though are the two following days.
(Figure: My mum decorating the Christmas tree. She's complaining they don't sell any longer tinsel made of tin or lead, but only aluminium which is too lightweight to hang properly. Originally, tinsel was made of silver.)


The maximal disaster is when the Holy Night falls on a Sunday, which means you are stuck with your family over the weekend and two more days during which shops are closed, restaurants are overbooked, and there is an endless amount of bad movies on TV (like usually all parts of 'Gone with the Wind' and the like). On the other hand, this means you might actually read the books you found under the tree about Feng Shui for your new apartment or something.

On the 24th, families often attend mass in the afternoon. Even those who usually don't, because it's kind of fun to see the children act the Christmas story. There, you meet all the neighbors and people you know from around town (who will inevitably tell you how you almost burned down the church when you were 6, or do you remember how you painted the school yard in 19-eighty something?)

Back from church, parents will have to occupy the children until 6pm. Presents are not brought by Santa Claus, but by the Christkind (see Lubos' nice post) and are put under the tree. I have no idea why, but for most people I know the Christkind comes at 6pm straight, and before this, grandparents are supposed to read stories, or children have to play Christmas songs on the piano (the only thing I can still play on a piano are these stupid Christmas songs that I had to practice from Easter on or something).

There is no real traditional dinner for Holy Night. My mum says, this year we'll have fondue. For lunch on Dec. 25th it's pretty common to have duck with red cabbage and dumplings.



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Friday, December 22, 2006

Stuck in a Boeing


*Yawn*

As Stefan already mentioned, JFK was a mess yesterday. Here's how I killed time while sitting on board of a flight that was #10 in line for take-off.

To be sung to the tune of 'Stuck in a Moment' by U2
(see here for original lyrics)



    "I'm not afraid
    Of any plane in this world
    There's no scary story

    That I haven't already heard

    I'm just trying to find
    A decent window seat
    A neighbor who's quiet
    And something to read.

    I never thought you were a fool
    Now you need to use the loo
    You've gotta stand up straight
    Shift your own weight
    This flight is going nowhere, baby

    You've got to get your bags together
    You've got stuck in a boeing
    And now you can't get out of it

    Don't say that later will be better
    Now you're stuck in a boeing
    And you can't get out of it

    I will not forsake
    The meals that they bring
    Since Chicken or Pasta
    Is still better than nothing

    I am still enchanted
    By the movies they brought to me
    Though the headphone was broken
    And the screen I couldn't see

    And you are such a fool
    To book flights like you do
    I know it's tough
    It's been more than enough
    Of what you don't really need now
    More delay

    You've got to get your bags together
    You've got stuck in a boeing
    And you can't get out of it

    Oh love, look at you now
    You've got yourself stuck in a boeing
    And you can't get out of it

    But I will certainly never again
    Book a trip with American

    I've got to run, which one is my gate,
    It's a long way to go, and I'm far too late.

    You've got to get your bags together
    You've got stuck in a boing
    And you can't get out of it

    Don't say that later will be better
    Now you're stuck in a moment
    And you can't get out of it

    And if the night runs longer
    And if the day won't last
    And if your bag got lost
    Along the stony pass

    And if the night runs over
    And if the day turns to past
    You'll earn bonus miles
    Along this stony pass

    It's just a moment
    This flight will pass"




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Manga-Nikolaus

She is here! The metal box from Toronto has brought Bee safely to Frankfurt. And I was amazed by this quite recent, fancy feature of real-time online tracking of flights. I could see that her plane was delayed and just crossing the Irish Sea when I was about to leave home for the airport, so I knew I had to wait one more hour before finally seeing her...


Since all shops in Germany will be closed over the holidays, from Saturday evening until Wednesday morning, we had to do some shopping this afternoon, food etc. Among the typical sweets one can get before Christmas are the Schokoladen-Nikoläuse, small Nikolaus figures made out of chocolate. They are wrapped in coloured tinfoil and have the classical red coat/white beard design.

So, we were quite surprised to see this funny Nikolaus, eh, figure, in a Manga-Look. I know that Mangas have become quite popular in Germany recently, but that they ever would take the job of Nikolaus? And, by the way, we were asking ourselves, is there anything similar to Christmas in Japan right now?

Thursday, December 21, 2006

Tagged!

I was tagged by Clifford in a chain-process with the following instructions:
  • Grab the book closest to you.
  • Open to page 123, go down to the fifth sentence.
  • Post the text of the next 3 sentences on your blog.
  • Name the book and the author.
  • Tag three people.

The book closest to me, believe it or not, is Albert Einstein's 'Über die spezielle und die allgemeine Relativitätstheorie'. The number on the last page of the index is 112. Will you allow I take the next book? Let me try. It has more than 123 pages! Here we go:



    "He was amazed. 'How can it be? I passed through three magic gates. I talked with Uyulala, then I fell asleep. But I can't possibly have slept that long.'

    'Space and time,' said Engywook, 'must be different in there'. "


From 'The Neverending Story' by Michael Ende.

Ah, now who do I tag? Let's see... I'll have to tag Alejandro, who's destined to have an interesting book near him... Then, oh yeah, lets take Tomasso and Lubos. Merry Christmas :-)

The Longest Night of the Year

Today is the shortest day of the year, followed by the shortest night, also called 'winter solstice'. The sun appears at its lowest point in the sky, and its noontime elevation appears to be the same for several days before and after the solstice. The word is derived from the Latin word solstitium, which combines sol for 'sun' and -stitium, for 'a stoppage' or 'stand still'. Thus, solstice means sun-stand-still.



The exact date of this years winter solstice is Dec 22nd 00:22, Greenwich Mean Time.

Folks, this means that from tomorrow on, days will get longer again!

It will be a very short night for me though, since I'm flying eastwards and loose a couple of hours.

It is generally believed that our date for the Christmas celebration, as well as many traditions are linked to ancient celebrations around the date of winter solstice. At least I can't recall the bible says something about hanging shiny stuff on evergreen trees, or kissing the poor guy who didn't notice the mistletoe. And for me, the days getting longer is a good reason to celebrate!

"In pre-historic times, winter was a very difficult time for Aboriginal people in the northern latitudes. The growing season had ended and the tribe had to live off of stored food and whatever animals they could catch. The people would be troubled as the life-giving sun sank lower in the sky each noon. They feared that it would eventually disappear and leave them in permanent darkness and extreme cold. After the winter solstice, they would have reason to celebrate as they saw the sun rising and strengthening once more. Although many months of cold weather remained before spring, they took heart that the return of the warm season was inevitable. The concept of birth and or death/rebirth became associated with the winter solstice. The Aboriginal people had no elaborate instruments to detect the solstice. But they were able to notice a slight elevation of the sun's path within a few days after the solstice -- perhaps by DEC-25. Celebrations were often timed for about the 25th. [...]

CHRISTIANITY: Any record of the date of birth of Yeshua of Nazareth (later known as Jesus Christ) has been lost. There is sufficient evidence in the Gospels to indicate that Yeshua was born in the fall, but this seems to have been unknown to early Christians. By the beginning of the 4th century CE, there was intense interest in choosing a day to celebrate Yeshua's birthday. The western church leaders selected DEC-25 because this was already the date recognized throughout the Roman Empire as the birthday of various Pagan gods.[...]

Many symbols and practices associated with Christmas are of Pagan origin: holly, ivy, mistletoe, yule log, the giving of gifts, decorated evergreen tree, magical reindeer, etc." (source)

One tradition though remained a mystery for me for a long time. Why do people put an angel on top of their trees? Well, here's why (from PlanetMike.com):

Xmas -- The tree angel tradition

Santa was very cross. It was Christmas Eve and NOTHING was going right. Mrs Claus had burned all the cookies. The elves were complaining about not getting paid for the overtime they had while making the toys. The reindeer had been drinking all afternoon and were dead drunk. To make matters worse, they had taken the sleigh out for a spin earlier in the day and had crashed it into a tree.
Santa was furious. "I can't believe it! I've got to deliver millions of presents all over the world in just a few hours - all of my reindeer are drunk, the elves are on strike and I don't even have a Christmas tree!


I sent that stupid Little Angel out HOURS ago to find a tree and he isn't even back yet! What am I going to do?"

Just then, the Little Angel opened the front door and stepped in from the snowy night, dragging a Christmas tree. He says "Yo, fat man! Where do you want me to stick the tree this year?"
And thus the tradition of angels atop the Christmas trees came to pass........

See also this interesting article about The Ancient Origins of the Winter Solstice, and the Wikipedia Entry on Solstice.

Wednesday, December 20, 2006

This and That

Some random things put together:
  • The arxiv will change its identifier scheme for new submissions beginning January 1st 2007. For more info, see here.


  • The well known German radio station 'Deutschlandfunk' (DLF) had a long report on Dec. 17th about 'Strings in the Crisis' (Strings in der Krise). This information was kindly provided by my husband, who actually listens to DLF. I like to call this station 'Depri-Funk', because no matter what they talk about, it's always depressing.

    If you know German, you can read the transcript on this site

    Strings in der Krise -- Physiker streiten um den rechten Weg zur Weltformel

    And if you really want, you can listen to the mp3 here.

    Be warned, if you do so, you'll have to endure a female voice intoning poems of the form "A Cosmos of slowness, Time is creeping, [...] Living in slow-motion. Dying in slow-motion [...] A Cosmos in reverse. The end is the beginning. Zebras are spitting grass to the ground. Men are dying [...] A cosmos of darkness [...]"

    ('A Kosmos der Langsamkeit.Zeit kriecht [...] Leben in Zeitlupe. Sterben in Zeitlupe [...] Ein Kosmos im Rückwärtsgang. Das Ende ist der Anfang [...] Zebras spucken Grashalme auf den Boden [...] Menschen sterben [...] Der Anfang ist das Ende [...] Ein Kosmos der Dunkelheit.')

    Jan Loius and Hermann Nicolai come to briefly express their excitement about string theory, and it is reported that: 'The Canadian physicist Lee Smolin finds in his book 'Zee Trobble Wiz Physiks' that strings are a failed thought experiment'. Later Nicolai says about the string debate caused by Smolin and Woit: "I wouldn't call that trouble, I perceived it somewhat as an amusement" ('Als Ärger würde ich das nicht bezeichnen. Ich habe das zum Teil etwas amüsiert zur Kenntnis genommen.') There is also the to-be-expected mentioning of L. Susskind and the anthropic principle, which is summarized stating that for Susskind it is 'a logical result of the mysterious six extra dimensions' ('eine logische Folge jener ominösen sechs Extradimensionen') that there exist 'universes that are inhabited only by speaking plants'.

    Quite interesting though is Thomas Thiemann's contribution in the end, where he briefly talks about his work on Loop Quantum Gravity. 'To describe the area of an A4* paper, it would take 1068 of these loops'. ('[...] um z. B. den Flächeninhalt von einem DIN-A4-Blatt zu beschreiben, bräuchte man 1068 von diesen Schleifen.')

    Since it is Depri-Funk, they finally come to the conclusion 'The situation [in LQG] is similar as it is in string theory. Researchers were able to properly write down the theory mathematically, but they aren't able to explain the world consistently. Both theories - strings as well as loops - are pure constructs. And both might remain speculations forever'

    ('Die Situation ist wie bei den Strings: Den Forschern ist es zwar gelungen, eine Theorie mathematisch sauber aufzuschreiben. Aber beide Theorien scheinen noch längst nicht in der Lage, die Welt schlüssig zu erklären. Beide Theorien - Strings wie Loops - sind bislang pure Konstrukte. Und beiden droht das Schicksal, für immer spekulativ zu bleiben.')


  • Weird Google searches that lead people to this blog:



    I also noticed with astonishment that my blog is currently the 4th hit for 'Peter Woit'. How did that happen?

  • Tomorrow morning, I'm stepping into a metal box in Toronto. It will make funny noises for too many hours, and when I step out of it, I'm hopefully in Frankfurt. That is, you are facing a slow-motion time on this blog.

  • And in the absence of anything more interesting to say, I'd like to point you towards this interesting blog, which I stumbled across today:

    Aaron in Afrika



* For the US visitors: A4 paper is used in the rest of the world, but is roughly the same size as letter format.

Tuesday, December 19, 2006

Naval Amphibious Base, Coronado

Today on Google Earth I saw...

"The Naval Amphibious Base (NAB) Coronado is located just across the bay from San Diego, CA. The base is situated on the Silver Strand, between the San Diego Bay and the Pacific Ocean. NAB Coronado is a major shore command, supporting 27 tenant commands, and is the West Coast focal point for special and expeditionary warfare training and operations. The amphibious base houses Commander Naval Surface Force, US Pacific Fleet, responsible for the training, maintenance and crews of the approximately 90 ships of the Pacific Fleet and Commander Naval Special Warfare Command, US Pacific Fleet. Also located there are most of the Naval Expeditionary and Naval Special Warfare units of the Pacific Fleet as well as the famed Navy Parachute Team, the Leap Frogs."

And here's the design the architect chose for the building:



You find it also on Google Maps.

Source: Google tracks Hitler to San Diego, and my office mate.


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Monday, December 18, 2006

The Lion sleeps tonight

Look at this cute video that my mum just sent me!


Isn't this just a totally amazing animation? (Google video has a version with slighly better quality, see here -- it's not exactly the same version as I just noticed).

Also nice is the string backlash, and the joke of the day :-).

The name of the guy who made the videos is Pierre Coffin. You find some more info on this website. You can stop that site from quacking by clicking on the ouch-button...

Sunday, December 17, 2006

300 years ago: Émilie du Châtelet born in Paris


In case you are French and want to read Newton's Principia in your language instead of the obscure Latin, you can resort to a translation, Principes mathématiques de la philosophie naturelle, that has been prepared by a very remarkable woman, Emilie du Châtelet, who was born 300 years ago, on December 17, 1706.

Emilie was the daughter of an aristocrat at the court of the Sun King, Louis Nicolas Le Tonnelier de Breteuil, and had the chance of being educated at home, instead of spending the time until her marriage in a convent, as it was then the custom for girls of her family background. She was very interested in mathematics and the sciences, and managed to get lessons by a young académicien named Maupertuis, of later fame for the formulation of the principle of least action.


Gabrielle-Émilie Le Tonnelier de Breteuil, Marquise du Châtelet (en.wikipedia.org)


For a long time, she has been known mainly as the companion and lover of the philosopher and writer Voltaire, with whom she shared many interests, literature, drama and opera, and - physics. Indeed, Voltaire had spent some time in England before, where he had learned about Newton's work and became fascinated by the simplicity of the universal law of gravitation and Newton's laws of motion. He had written about this, among many other things, in his lettres philosophiques, and was about to prepare a long, popular exposition of Newtonian physics, the Elémens de la philosophie de Neuton, when he met Émilie.


The frontispiece to Voltaire'’s Elémens de la philosophie de Neuton, with Émilie du Châelet illuminating Voltaire with the light of insight coming from Newton (Rare Books Division, New York Public Library). The Elémens saw 26 editions between 1738 and 1785 and contributed enormously to the popularization of Newtonian physics in France.


Praise of England in the letters philosophiques had stirred some trouble for Voltaire in Paris, so he was especially happy when Émilie invited him to her husbands manor, the Château de Cirey, far away from the capital, and close to the border of Lorraine, which was not part of France at that time.

At Cirey, they spent happy and very creative and productive years together. They established a small theatre in the castle, and a physics laboratory. Here, they conducted experiments on the nature of fire, preparing contributions to a contest organized by the French Academy of Sciences.


The Château of Cirey-sur-Blaise in eastern France ((www.trekearth.com)


Émilie continued her studies of maths and physics, under the guidance of Clairault and the German mathematician König. She started to write a textbook on physics intended for the education of her 12-year old son. The result, the Institutions de physique, was praised as an excellent exposition, but over the head of most of its potential readers. It contained a discussion of Leibniz ideas and his concept of vis viva, the living force, which we know today as the kinetic energy. It's hard to imagine now that it took several decades of intense debates before the concepts of conservation of linear momentum and kinetic energy in simple mechanics were neatly formulated and firmly established. Anyway, Émilie's exposition of what we now call kinetic energy, the quantity proportional to the square of the velocity - is the reason that she is marketed sometimes as a direct precursor of Einstein and his famous formula E = mc2.

In 1745, she embarked on her largest scientific project - the translation of Newton's Philosophiae naturalis principia mathematica, based on the third Latin edition from 1726. She managed to finish this tedious work just days before her death, too early and under quite dramatic circumstances in September 1749.

I find it difficult to gauge her scientific achievements, not the least because of the big time lag since the days of the enlightenment. She didn't contribute lasting original research, it seems, but her expositions and writings most probably was instrumental in the shift of the center of gravity in mathematics and physics from Newton's England to France - Laplace, one of the most prominent of the French mathematicians of that time, was born in the year she died. Anyway, La Marquise du Châtelet was a very remarkable woman, and her life demonstrates in a wonderful way how science can be and should be part of general culture.


In France, at least, it seems that she has become kind of a celebrity at last, honored at her tricentennaire as the first woman scholar - there is even a nice children's book about her.



There are several places on the Web to read more about Émilie du Châtelet, e.g.

Passionate Minds by David Bodanis is a recent biography about her.


About the vis viva controversy, there was an article in the October 2006 issue of Physics Today, see e.g. here.



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Saturday, December 16, 2006

The National Data Book

The US Census Bureau has released the 2007 statistical abstract. "The Statistical Abstract of the United States, published since 1878, is the authoritative and comprehensive summary of statistics on the social, political, and economic organization of the United States."

The full report with all tables has roughly 1,400 pages, and is available online. You find the abstract on this website.

Some interesting statistics:


  • The 2005 population of US residents is ~ 296,410,000 (Table 2).


  • The number of admitted immigrants increased from 2004 to 2005 and exceeded the level from 2001, after a significant drop in 2003 (Table 6).


  • 15.7% of US citizens (11.2% of children) have no health coverage (numbers from 2004). The rate of non-covered persons is the highest in Texas (25% total /21.4% children), followed by New Mexico (21%/15.3%) and Florida (19.9%/15.1%) (Table 145).


  • The most dangerous home furnishing item is the bed. In 2004 it caused 518,441 injuries. Also interesting: 121,094 people suffered injuries caused by their footwear. The statistic counts emergency room treated cases nationwide in 2004 (Table 173).


  • The number of reported cases of AIDS decreased slightly from 2003 to its 2004 value of 44,108 (Table 175).


  • South Dakota is the only state that did not report any case of Syphilis in 2004 (Table 176).


  • The percentage of current cigarette smokers decreased from 2000 to 2004, the average value in 2004 was 20.8%. From the listed groups, black women have the lowest percentage (16.0%) of smokers (Table 191).


  • 7.9 % of US citizens age 12 and older classify themselves as 'current users of illicit drugs'. The caption says 'Current users are those who used drugs at least once within month prior to this study'. (Table 194)


  • 65.3 % of US citizens are overweight. The statistics I printed has a chocolate smear. (Table 198).


  • 2004 in the land of plenty: 13,494,000 households in the US were food insecure. The number of households with hunger among children raised from 0.5 % in 2003 to 0.7 % in 2004 (Table 2004). Though recently the department of agriculture has defined hunger as a non-existent state, see also 'Very low food security'.


  • The average US citizen consumed 24.6 gallons of coffee, and 25.2 gallons of beer in 2004 (Table 201).


  • 74.1% of doctorates in physical sciences (astronomy, physics and chemistry) are male, 42.0% are foreign citizens, 79.1% are white (status 2004, Table 789).


  • In the last quarter of 2005, 22.5% of flights arrived late (more than 15 min) at major US airports. The worst airport is Newark International with 41.9% (Table 1055).


  • 6,894 people filed consumer complaints against US airlines in 2005 (Table 1056).


  • The number of alternative fueled vehicles in use increased slightly from 2003 to 2004 (Table 1075).


  • 42,636 people died in, or as a cause of car accidents in 2004 (Table 1083).


  • The median income of households in 2004 was US$ 38,453. The median income White only was $40,469, Black only $23,372. 15.5% of all households have an income under $15.000, and 15.7% have an income over $100.000. (Table 671 and 672).


  • The medium household income is the highest in Connecticut with $60,528, and the lowest in West Virginia with $31,504 (Table 687).


  • 36,997,000 people (12.7%) live below poverty level, status 2004 (Table 692).


  • The US counts 3,510,000 top wealth holders with net worth of $ 1 Million or more. Most of which live in California, followed by New York and Florida (Table 700).



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Friday, December 15, 2006

Beauty in Physics

As a postscriptum to my earlier post about The Beauty of it All, here is a photo of my latest painting. I made it after a sketch I took from Chanda's back during a seminar.



[Click to enlarge]


Yes, the lady on the photo is the same Chanda who also wrote the guest post at CV, see also my post about Diversity in Science.

The painting is 20'' x 24'', acrylic on canvas.



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Thursday, December 14, 2006

Global Cooling

Exactly one year ago, I visited Waterloo for the first time. I was standing in snow knee-deep, and the outside temperature was -15 C. Yesterday, when I went to work, the thermometer showed 8 C. How could I not be interested in climate change?! Here's what I read yesterday:




If you follow the news above, you'll see how the content gets gradually diminished. None of the articles above links to the actual meeting, nor do they properly reference the original paper they are talking about (the first one does at least mention the title and the journal). If you are interested, here is

The website of the AGU 2006 Fall meeting

And here is the original paper:

Climatic consequences of regional nuclear conflicts
Atmos. Chem. Phys. Discuss., 6, 11817-11843, 2006

A. Robock, L. Oman, G. L. Stenchikov, O. B. Toon, C. Bardeen, R. P. Turco

We use a modern climate model and new estimates of smoke generated by fires in contemporary cities to calculate the response of the climate system to a regional nuclear war between emerging third world nuclear powers using 100 Hiroshima-size bombs (less than 0.03% of the explosive yield of the current global nuclear arsenal) on cities in the subtropics. We find significant cooling and reductions of precipitation lasting years, which would impact the global food supply. The climate changes are large and long-lasting because the fuel loadings in modern cities are quite high and the subtropical solar insolation heats the resulting smoke cloud and lofts it into the high stratosphere, where removal mechanisms are slow. While the climate changes are less dramatic than found in previous "nuclear winter'' simulations of a massive nuclear exchange between the superpowers, because less smoke is emitted, the changes are more long-lasting because the older models did not adequately represent the stratospheric plume rise.

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Wednesday, December 13, 2006

PI

3.14159265358979323846264338327950288419716939937510582097494459230
781640628620899862803482534211706798214808651328230664709384460955058
223172535940812848111745028410270193852110555964462294895493038196442
881097566593344612847564823378678316527120190914564856692346034861045
432664821339360726024914127372458700660631558817488152092096282925409
171536436789259036001133053054882046652138414695194151160943305727036
575959195309218611738193261179310511854807446237996274956735188575272
489122793818301194912983367336244065664308602139494639522473719070217
986094370277053921717629317675238467481846766940513200056812714526356
082778577134275778960917363717872146844090122495343014654958537105079
227968925892354201995611212902196086403441815981362977477130996051870
721134999999837297804995105973173281609631859502445945534690830264252
230825334468503526193118817101000313783875288658753320838142061717766
914730359825349042875546873115956286388235378759375195778185778053217
122680661300192787661119590921642019...


Want more? Click here to get one million and a quarter digits of Pi!



Yesterday, I read that the bible says Pi equals 3. Consequently I thought, gosh, somebody will insist to replace Pi with three in all schoolbooks, so they are in agreement with the bible. It didn't take me long to find out this was hardly a new concern, and has already status of an urban legend.

For the basics: Pi is the ratio of a circle's circumference to its diameter (in Euclidean geometry). It is named "π" because it is the first letter of the Greek words περιφέρεια 'periphery' and περίμετρος 'perimeter', i.e. 'circumference'. And it's not equal to three. In fact it's roughly equal to the long number shown above, the essential thing being the dots in the end.

But some more interesting info: Pi is a transcendental number, which means it can not be written as the solution (root) of a polynomial with coefficients in the integer numbers. This also implies that the number of digits after the point is infinite, they do never repeat, and every possible sequence appears at some point* (see here for the probability of finding some, and here for searching them).

Since this so far only explains what Pi is not, it seems some people are still concerned whether it actually exists. Well, this might sound somewhat philosophic, but I mean, you can't just write it down and say, there it is. The definition that I recall is that Pi/2 is the first zero of the sinus function. Which seems to me quite easy to prove that it exists (the function being smooth and having a sign change and all). If you don't want to use Euler's number for the sinus (another transcendental number), the sinus function can be defined as an infinite polynomial, which I would write down here, if latex could speak on my blog...

See also:


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Monday, December 11, 2006

A Tribute to my Granny

One of my favourite cookies are Kokosmakronen, not only because they taste good, but because they are quite easy to make. This is baking for the non-expert. For the sophisticated advises, I recommend Clifford's blog. For a recipe of a completely different kind see also: a paper recipe.

Ingredients:

  • 6 egg whites
  • 400 g shredded coconut (unsweetened)
  • 300 g fine, white sugar
  • 1 pg vanilla sugar
  • 1 teaspoon salt


Preparation:

  1. make sure oven works1
  2. cut finger nails
  3. download Bing Crosby's White Christmas
  4. turn on iPod player
  5. turn off BlackBerry

The Making Of:





Collect ingredients. While doing so, smash an egg and bump your head on the cabinet when wiping up the floor. Also, make sure the digital camera is farther away than the average interaction distance of cookie dough (some meters).
Separate eggs. It's not as difficult as they told you. And it's not a cheese cake, so it's not so crucial. If shell drops in, don't worry. For reasons I don't fully understand I always find the shell pieces on the bowl rim later and can pick them out.
Beat egg whites thoroughly and patiently, until inscribed Greek symbols remain clearly visible. Keep in mind what my Granny used to tell me: back then in 19 twenty-something, they had to beat roughly one hour by hand. Those were the days...
Fold in vanilla, salt, coconut and sugar. If the result looks suspiciously liquid, add some teaspoons of flour or so. While the sky over Waterloo is covering your car with several inches of white stuff you'll have to scrape off tomorrow, whistle with Bing Crosby to I'll be home for Christmas.
Preheat oven to something in the middle range, but not too hot. Try to get the stuff on a baking sheet in small lumps. I recommend using two teaspoons. Leave at least 1 inch to each side. Oops, forgot to mention, better use some non-stick spray or something.
Make sure to put the pan lid on the front right plate, because it isn't tight and the oven looses hot air. Open a bottle of wine2. Put cookies into oven. Go to answer some comments on your blog, let cookies burn, get drunk and repeat procedure the next day.
Baking time is roughly 20 minutes, depending on your stove, the eggs, and the fine-structure constant. Kokosmakronen aren't really baked, but rather dried. Result should be light gold brown on the outside. If they got too hard or dry, put them in a plastic bag for some days. If they burn, break off burnt rim and use plenty of chocolate coating.


Acknowledgements:

This post is dedicated to my Granny who tought me how to separate eggs, and who died at age 95 six months ago. Reaching such high age is definitly due to eating excellent Kokosmakronen each Christmas.

Disclaimer:

The author of this blog is neither responsible for potential hangovers, nor damage of stoves, mixers, digital cameras or other kitchenware.



Footnote 1: But don't touch the buttons.
Footnote 2: The white wine was a VQA Jackson-Triggs, 2004 Grand Reserve Chardonnay, Niagara Peninsula, which was fairly decent and recommendable.

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Sunday, December 10, 2006

Did you know... (III)

... why the toast is a toast?

Yesterday, I went to the groceries store and was greeted by an ad saying: It's the toast season! Okay, I wondered, what kind of a tradition is this? Do Canadians toast maple leaves on their bread or what? Upon second inspection however, (I think I need new glasses) the sign turned out to stand in front of the wine department.


So here is why the toast is called toast:

"The word derives from the Latin word 'tostare' (to scorch or roast - i.e. toast ). From Classical times it was common to flavour wine by floating small pieces of toasted bread in it. Sometimes these sippets would be flavoured with spices; at other times the carbon alone would mellow the wine."

Wikipedia clarifies appropriate toasting behaviour in the US and Canada, apparently written by someone who was tired of endless toasty speeches while he had to hold a glass of wine in mid air:

"The following guidelines apply specifically to toasting in Canada and the United States:


  • Most people will lightly touch glasses when giving a toast, often saying "toast", "cheers" or a short phrase such as "to us". Toasting without touching glasses is increasingly popular and is regarded by some as a slightly more sophisticated mode of behavior.
  • Except during formal occasions [...] it is not very common to "propose a toast" in the more formal sense. However, when someone does make such an gesture, it is almost invariably met with approval regardless of the setting or the occasion.
  • If someone wants to "propose a toast as well", this second toast should have a different focus than the first [...] Ideally, this toast is briefer than the first so as not upstage it. Subsequent toasts, if any, should even more succinct.
  • Americans and Canadians typically toast only once per gathering, if at all. Even lifting one's glass and saying "cheers" each time a new drink is poured isn't in line with local etiquette and, while not impolite, may be seen as a bit tedious."


Also: since it's the toast season, have a close look at your breakfast before you eat it. It might turn out to have heavenly messages on it. One of the most absurd stories I've heard about eBay is certainly that of the toast with the Virgin Mary face that has been sold for $28.000. Even though a bite is missing from it. What's even more absurd than this toast being sold for such an amount is that it was bought, not by a religious nutcase, but by an internet casino saying the toast had become a "part of pop culture".


Cheers!

See also: Make a toast in 50 different languages

And:


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Saturday, December 09, 2006

Deformed Special Relativity

My prediction about the number of comments on Joe Polchinski's review of Peter Woit's and Lee Smolin's books over at CV wasn't so bad, and they are still coming. I would like to use the opportunity to write about a topic I have been working on for some while, and which I believe was mentioned in the discussion, namely deformations of special relativity (DSR).

In May, I gave a seminar at UCSB about my recent work on the topic, which I have briefly summarized in the post The Minimal Length Scale. Since I recall that Joe Polchinski was present that day, I sadly conclude that the seminar wasn't very illuminating, so I'll try to clarify some things. In the beginning though, I should add a note of caution since my work on DSR is not in complete agreement with what the standard approach is. You find further details in my papers

To set the context, in the review Joe Polchinski writes:

    Smolin addresses the problem of the Planck length (“It is a lie,” he says). Indeed, Planck’s calculation applies to a worst-case scenario. String theorists have identified at least half a dozen ways that new physics might arise at accessible scales [6], and Smolin points to another in the theories that he favors [7], but each of these is a long shot. [...]

With reference to the footnotes:

    [6] The ones that came to mind were modifications of the gravitational force law on laboratory scales, strings, black holes, and extra dimensions at particle accelerators, cosmic superstrings, and trans-Planckian corrections to the CMB. One might also count more specific cosmic scenarios like DBI inflation, pre-Big-Bang cosmology, the ekpyrotic universe, and brane gas cosmologies.

    [7] I have a question about violation of Lorentz invariance, perhaps this is the place to ask it. In the case of the four-Fermi theory of the weak interaction, one could have solved the UV problem in many ways by violating Lorentz invariance, but preservation of Lorentz invariance led almost uniquely to spontaneously broken Yang-Mills theory. Why weren’t Lorentz-breaking cutoffs tried? Because they would have spoiled the success of Lorentz invariance at low energies, through virtual effects. Now, the Standard Model has of order 25 renormalizable parameters, but it would have roughly as many more if Lorentz invariance were not imposed; most of the new LV parameters are known to be zero to high accuracy. So, if your UV theory of gravity violates Lorentz invariance, this should feed down into these low energy LV parameters through virtual effects. Does there exist a framework to calculate this effect? Has it been done?

There is a reply to that question in comment #20 by Brett:

    I wanted to answer the question the question posed in [7].
    In short, this is a significant problem for any theory that predicts Lorentz violation. [...]


    The most explicit calculation of this that has been published is, I believe, in Collins, et al. Phys. Rev. Lett. 93, 191301 (2004). They take a Lorentz-violating cutoff and show how it affects one low-energy function. [...]

Which refers to this paper:
There follows a comment by Jaques Distler on Lorentz violation, some other comments, and comment #30 by Robert comes back to the question

    IIRC the way Lorentz violation is supposed to show up in loopy physics is that the dispersion relation is violated and the speed of light depends on energy (showing up in early or late arrival of ultra high energy gamma ray burst photons compared to ones of lower energy). The idea is that even if the relative effect is quite small the absolute size could be measurable as these photons have traveled across half the universe. Does anybody have an understanding of how this effect arises? [...] Which calculation this referes to? What do I have to compute to get this energy dependent speed of light?

Then, in comment #43, Joe Polchinski partly answers his own question:

    Brett #20,22: Thanks for the reference, this is certainly what I would expect. I understand that there is the hope for a `deformed algebra’ rather than a simple violation, but to an outsider it seems that what is being done in LQG is to return to pre-covariant methods of QFT, cut things off in that form, and hope for the best. It would be good to see some calculations.



Now let me add my comments:

The idea of deforming special relativity is to allow two invariant parameters of the transformations between reference frames. The one invariant is the speed of light, the other one is the regulator in the ultra violet, alias a maximal energy scale. This energy scale is usually identified with the Planck energy ~ 1019GeV. If one believes that the Planck energy acts as a maximal energy scale, then all observers should agree on this scale to be maximal. Since usual Lorentz transformations do not allow this (one can always boost an energy to arbitrarily high values), one needs a new type of transformations. These turn out to be non-linear in the momentum variables, which is the reason why they usually do not show up in standard derivations of Lorentz transformations, where one assumes linearity.

The construction of such transformations that respect the upper bound on the energy scale is possible, and they can be explicitly written down. The approach has been pushed forward notably by Giovanni Amelino-Camelia, who has written an enormous amount of papers on the topic. Unfortunately, I find his papers generally very hard to read and confusing. A very readable and clear introduction that I can recommend is e.g.

These theories do not break Lorentz invariance in the sense that they do not single out a preferred restframe. Instead, the Lorentz transformations (as functions of the boost parameter), are modified at high values of the boost parameter. This allows the maximal energy to be an invariant quantity. You can find an explicit example for such transformations e.g. in gr-qc/0303067, Eq. (19). What is deformed in this approach, as far as I understand it, is not the algebra itself, but the action of the generators on the elements of the space.

A deformation of Lorentz invariance consequently leads to a new invariant scalar product in momentum space, which means one has a modified dispersion relation. Under quantization, the approach is also known to imply a generalized uncertainty principle, which stems from the modified commutation relations. Theories of this type can but need not necessarily have an energy dependent speed of light (for details about these relations see e.g. hep-th/0510245).

In contrast to this, the paper mentioned by Brett in comment #20 by Collins et al explicitly examines a scenario with violation of Lorentz invariance. As they state already in the abstract "Here, we explain that combining known elementary particle interactions with a Planck-scale preferred frame gives rise to Lorentz violation at the percent level, some 20 orders of magnitude higher than earlier estimates[...]" I am reasonably sure this was not the scenario Lee Smolin is referring to in his book. I vaguely recall he actually writes something about Giovanni -- it implied a knife being put on somebodies throat or so. Unfortunately, I lent the book to my office mate, so I can't look it up.

If one introduces a hard cut-off in a momentum integration without making use of a modified Lorentz-symmetry one runs of course intro problems. With the use of deformed transformations however, this problem can be circumvented. A good way to think about it is in my opinion to picture momentum space not as being a flat, but a curved space. In this case, the integration over the volume in one or more directions can be finite. The non-flatness of the space shows up in the volume element via the square root of the determinant of the metric tensor, which can improve the convergence of loop integrals. By construction, the integration is invariant under the appropriate transformations in that space. In this approach, it is exactly the additional factor (square root of g) in the volume element that makes the integration invariant.

Another way to think about it is to consider a non-linear relation between wave-vector and momentum, in which case the role of the convergence-improving factor is played by the Jacobian determinant of the functional relation between both, see e.g. hep-ph/0405127.

A quantum field theory with DSR can be formulated as a theory with higher derivatives in the Lagrangian (see e.g. hep-th/0603032, or gr-qc/0603073). In fact, as I like to point out, in a power series expansion one needs arbitrarily high derivatives, since a finite polynomial could never reproduce an asymptotic limit. If one writes down a series expansion to get an effective theory, one has corrections in higher order interactions suppressed with powers of the Planck mass as one would expect. Each of these terms is Lorentz invariant, provided the quantities are transformed appropriately. However, in my opinion, such an expansion is not so very helpful, since the important thing is the convergence of the full series. These higher order terms come with the usual constraints on the interactions. I also don't see a point in examining them in great detail, since we don't know anyhow what other funny things might happen to the particle content at GUT or Planck scale energies.

The status of a full quantum field theory with DSR is presently unfortunately still very unsatisfactory. It is a topic I am working on myself, and I am very optimistic that there will be some progress soon. It is however possible to make some general predictions, using kinematic arguments, or just by applying the modified transformations. As mentioned by Robert above, the time of flight being energy dependent (in the case of DSR with an energy dependent speed of light) is an example for such a prediction. Some details about this can be found in

My interest in DSR arises from the fact that it is based on a very general expectation that we have about quantum gravity, which is that the Planck energy acts as a regulator in the ultra violet. In my works, I have mainly examined in how far it is possible to include this property into standard quantum field theories as an effective description of what should actually be described by a full theory of quantum gravity. I am not an expert as to how DSR is related to LQG, and how strictly this connection can be established.


Update: See also what the expert says.

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Thursday, December 07, 2006

Have a Stringy Christmas

What's new? Joe Polchinski's review 'All Strung Out?' of Peter Woit's and Lee Smolin's books over at CV (via Asymptotia). The choice of the title is quite ironic. I wonder if he knew this had almost been the title of Lee's book (without the question mark, I presume). The review is worth reading, whether you like or didn't like the books and/or authors.

Besides this new round in the discussion (I predict of order 200 comments over at CV), look what I found in my inbox: Stringy Christmas greetings from last December :-)

----- Original Message -----
From: "D****** M*******"
To: "KITP Lunch List"
Sent: Thursday, December 08, 2005 4:05 PM
Subject: [strings05] song lyrics

Here are the lyrics:

[...]

Song #2: The Maldacena, by Jeff Harvey (1998)

You start with the brane
and the brane is BPS.
Then you go near the brane
and the space is AdS.
Who knows what it means
I don't, I confess.
Ehhh! Maldacena!

Super Yang-Mills
with very large N.
Gravity on a sphere
flux without end.
Who says they're the same
holographic he contends.
Ehhh! Maldacena!

Black holes used to be
a great mystery.
Now we use D-brane
to compute D-entropy.
And when D-brane is hot
D-free energy.
Ehhh! Maldacena!

M-theory is finished
Juan has great repute.
The black hole we have mastered
QCD we can compute.
Too bad the glueball spectrum
is still in some dispute.
Ehhh! Maldacena!


#############################################################
This message is sent to you because you are subscribed to
the mailing list strings05@kitp.ucsb.edu.


----- End of Original Message -----

Tuesday, December 05, 2006

Nikolaus

December 6th is Nikolaus day in Germany, a tradition that comes very close to the North American Christmas. The evening before Nikolaus, children put a boot in front of the door. If they were good children in the past year, they will find the boot filled with goodies the next morning. Parents shamelessly use the occasion to demand that every single shoe in the household has to be cleaned.


Unlike cheerful Santa Claus however, Nikolaus comes with a dark companion, called Knecht Ruprecht. Knecht Ruprecht doesn't wear red and white, but black and brown, and he carries with him a rod and a sack. If you haven't been a good kid, or didn't convincingly clean your stupid boots, you'll get hit with the rod. If you really messed it up (say, by writing silly comments on other people's blogs), you'll get packed in the sack and carried away to his home in the black forest.

Well, yes, that's not politically correct, but that's how the story goes. Another thing that is probably politically incorrect is how my granny used to tell the story. In her version, the evil Knecht Ruprecht wasn't from the black forest, but was actually black and from Africa. If you want to see what Knecht Ruprecht allegedly looks like, check the Wikipedia entry Companions of Saint Nicholaus. Then have another look at your boots, and reconsider if you really think they are clean enough.

Though the origin of the European Knecht Ruprecht tradition is kind of unclear, Saint Nicholas goes back to a real person. Saint Nicholas lived in the 4th century, when he was bishop of Myra, which is today Demre in the Antalya province of Turkey. Saint Nicholaus had a reputation for secret gift-giving (though I wonder how secret it can have been if he had a reputation for it).

Saint Nicholaus is also the patron saint of sailors.

Have a wonderful Christmas season, and keep your boots clean!

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Sunday, December 03, 2006

Book Cover Physics

Books which want to be sold need attractive covers besides cogent content - that's because potential readers who pick up new publications at bookstores by chance are still an important target group for publishers. Even the mechanisms of selling books on the internet are not so different yet.

For books on scientific topics, it has always been quite common to use artwork on the cover that is both aesthetic and appealing and related to current trends in science, thus, to use illustrations that are, in a sense, icons of the scientific development of their time. Bee's recent post about Bacon reminded me of a wonderful example of an (in my eyes) extremely attractive book illustration which demonstrates this point: It is the frontispiece of the Instauratio Magna, the major work of Francis Bacon containing the Novum Organum, where he explains his new method for scientific investigation.



It's not a cover illustration as we know it today, since back in 1620, when it was published, books were just bound in heavy leather, and there were no book jackets. But the ships that come in from the wide, open sea of unexplored knowledge, and bring with them funny plants and animals from remote and newly discovered parts of the world are a beautiful metaphor for Bacon's' ideas at a time when British mariners started to rule the waves.

Modern tools of exploration are not any more large ships, but instead test tubes, microscopes, telescopes, space probes, and particle accelerators. And indeed, spectacular photos by the Hubble Space Telescope feature on the covers of many books on astronomy, cosmology, or even string theory. However, with the huge amount of amazing Hubble pictures, the one icon picture is missing - a role maybe best taken over by the COBE, then WMAP maps of the cosmic microwave background, as far as astrophysics and cosmology are concerned.

Here, following a severe personal bias, I want to talk a bit about two beautiful illustrations coming from particle physics - one quite old by now, but still often in use, the other more recent, and, I guess, with a huge potential for use in the near future ;-)







The first illustration shows a chaos of curved, fancy blue lines against an amber background. It comes with several degrees of changes applied to the original, and it was used recently on the covers of the Jonathan Cape edition of Not even wrong and The Scientist as Rebel by Freeman Dyson, New York Review Books (2006). The photo also features on The Particle Garden: Our Universe As Understood by Particle Physicists by Gordon Kane (Helix Books, Addison Wesley Publishing Company, Paperback, July 1996), Understanding the Universe: From Quarks to the Cosmos by Don Lincoln, (World Scientific Publishing Company, October 2004, Paperback), and the now out-of-print 1994 Canto edition of Quantum Physics: Illusion or Reality? by Alastair Rae - that's where I had seen it for the first time, as far as I remember.

There may be many more book covers where it has been used, perhaps someone knows of some other titles.

The origin of the illustration has been discussed before on Peters blog, and Peter refers to the interactions.org database.

But the original photo is from CERN, and can be found with more information and links at the CERN Document Server, cdsweb.cern.ch/record/39312. Included there is also a short list of some publications where it has been used.


cdsweb.cern.ch/record/39312


As for the content, the photo shows, according to the CERN record, an artistically enhanced picture of particle tracks in the BEBC, Big European Bubble Chamber. Bubble chambers were the devices of choice for the detection of the tracks of charged particles created in all kinds of nuclear and elementary particle collisions in the 1960s and 1970s. Filled with a liquid that can be brought in an overheated state, charges particles which cross the liquid serve as the seeds where boiling set in, and thus, tracks are marked by traces of small bubbles of boiling liquid.

More background on the CERN image can be found in the August 2004 issue of the CERN Courier, with the figure caption Picture postcard: Famous postcard view of a neutrino interaction in BEBC (the Big European Bubble Chamber) filled with a neon-hydrogen mixture. Indeed, the picture was sold as a postcard at CERN when I was there for the first time in 1999 - I had sent this postcard to several friends then!

Concerning the science behind the picture, it seems that the BEBC was used mainly for neutrino experiments - the December 1998 issue of CERN courier has more about that, www.nu.to.infn.it/exp/all/bebc links some papers related to BEBC experiments, and just citing from CERN Bulletin 20/2004, which shows this photo of the installation of the BEBC:



cdsweb.cern.ch/record/41546: The vessel of the Big European Bubble Chamber, BEBC, was installed at the beginning of the 1970s. The large stainless-steel vessel, measuring 3.7 meters in diameter and 4 metres in height, was filled with 35 cubic metres of liquid (hydrogen, deuterium or a neon-hydrogen mixture), whose sensitivity was regulated by means of a huge piston weighing 2 tonnes. During each expansion, the trajectories of the charged particles were marked by a trail of bubbles, where liquid reached boiling point as they passed through it. The first images were recorded in 1973 when BEBC, equipped with the largest superconducting magnet in service at the time, first received beam from the PS. In 1977, the bubble chamber was exposed to neutrino and hadron beams at higher energies of up to 450 GeV after the SPS came into operation. By the end of its active life in 1984, BEBC had delivered a total of 6.3 million photographs to 22 experiments devoted to neutrino or hadron physics. Around 600 scientists from some fifty laboratories throughout the world had taken part in analysing the 3000 km of film it had produced.

The BEBC is now on display on a lawn near the CERN cafeteria, where it looks like some alien spaceship ;-)...



cdsweb.cern.ch/record/41091: Group of belgian physics teachers in front of BEBC bubble chamber, in March 2000

Bubble chambers, like emulsion film techniques or similar methods to record tracks of particles, have one big disadvantage: events are fixed on film, and to do a physics analysis, thousands of photos have to be checked "by hand". This is a very tedious job, which often was done by women "scanners".



LBNL Image Database 96602983: Operator, Barbara Srulovitz, maps particle tracks with Alvarez Scanning and Measuring Projector.

In a sense, the huge BEBC was a kind of dinosaur, the end point and culmination of this type of detection device. For an automized analysis using electronic computers, it would have been nice to have complete information on all particle tracks available in some electronic form. That's what can be achieved with wire chambers, or, a widely used variety of these kinds of detectors, time projection chambers (TPCs).

A time projection chamber is a large chamber filled with gas. High-energy charged particles emerging from a collision event will ionize this gas along their paths, leaving behind tracks of electrically charged gas molecules. The whole TPC is subject to a homogenous electric field, which moves the pattern of tracks drawn in electrically charged gas molecules towards small-meshed grids of wires. There, the ionized gas molecules create electrical signals, and from the location of the wires which are triggered and the time delay between the collision and the detection at the wire (which is the time the ionized gas molecules need to drift from the position of the track to the detector wire), it is possible to reconstruct the complete three-dimensional pattern of all tracks of charged particles emerging from the original collision. TPCs are now in use since more than 25 years and are a central component of many particle physics experiments. I am not an experimentalist, so I have no inside view of all the complexities and difficulties which are part of this data gathering process. But I am amazed that it is possible to reconstruct particle tracks with a spatial resolution below one millimeter, using state-of-the art TPCs!

In collider experiments, such as at RHIC, TPCs are large cylindrical chambers, with the central axis of the cylinder coinciding with the beam axis and the collision point at the centre of the chamber. A TPC is the main detecting device of the STAR experiment, the Solenoidal Tracker at RHIC. This photo, which is part of a series of photos provided by the Lawrence Berkeley National Lab, shows the TPC of STAR.



It was with data from the TPC of STAR that this graphical representation of one of the first gold-gold collisions at RHIC was created in June 2000.



The graphics shows the projection of the tracks of electrically charged particles emerging from the gold-gold collision. There are in the order of 3000 charged particles emerging from central collisions, and the radial motion of these particles is displayed in the figure.

The analysis of the radial motion of all the particles produced in a heavy-ion collision provides such observables as the elliptic flow, which describes the deviation of the pattern of motion from perfect radial symmetry for non-central collisions, and which allows to estimate the viscosity of the hot and dense nuclear matter created in the collision.

But this is a second step of the analysis: First, the tracks, and momenta, of as many particles as possible have to be determined. These tracks make up the wonderful picture from STAR, with its striking resemblance to the iris of an human eye. It shows a central part of the science of heavy-ion physics in an eye-catching way, and features in many talks and articles about heavy-ion physics. This STAR picture has become kind of an icon of heavy-ion physics.








Which brings me back to my initial topic of the book covers: The RHIC "iris" of the STAR-TPC has made it, as far I could see, on the covers of The QCD Vacuum, Hadrons and Superdense Matter by Edward V. Shuryak, (World Scientific, 2nd edition, 2004), Alpha and Omega: The Search for the Beginning and End of the Universe by Charles Seife (Viking, 2003), and Quark Gluon Plasma 3 edited by Rudolph C. Hwa, and comment writer X. N. Wang (World Scientific, 2004)

But considering the dark and mysterious appeal of this photo, my guess is that we will see it more often on book covers of future, new releases.

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Low Food Security

The lucky citizens in the land of plenty will never again have to endure hunger. The US Department of Agriculture has replaced the condition of 'hunger' with that of 'very low food security'. Though I'd agree with Mark Nord, the lead author of the report, that 'hunger' is not a scientifically accurate term, I find the chosen alternative not so much better. I'd have said the majority of people in the so-called western civilization lives in a state of constant very low food security: one is never quite sure what it is one actually eats. Shockingly, the report finds: "[...] that 12 percent of Americans — 35 million people — could not put food on the table at least part of last year. Eleven million of them reported going hungry at times."

See also:

Political Gateway: USDA eliminates 'hunger' from reports
Seattle Times: U.S. agency changes "hunger" to "very low food security"
SF Chronicle: My stomach is touching my back


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