Saint Hedwig

Of course, when I saw this church's name on the map, I had to visit. It actually has an interesting history, as it is the main cathedral for the Catholic diocese that includes Berlin (I guess the correct term is the seat of the archbishop of Berlin). It was also a good thing, because it turned out that there was a free organ concert that evening, my last evening in Berlin.

Side view of St Hedwig's, showing the domes.

Front entrance of St Hedwig's. There was much construction, as can be seen, in the platz surrounding the cathedral, as is true of much of Berlin.

Organ in St Hedwig's.

I was excited, because the poster for the concert said that some of Arvo Pärt's music would be played. I was introduced to Pärt when I went to a concert at Stetson University about a year ago. It was a duet with piano and tuba - being an old tuba player myself, I had to go. One of the pieces they played was Pärt's "Spiegel im Spiegel." Normally it is piano/violin, but these guys reworked it for piano/tuba. It was excellent. I've since heard it (in a recording) with the standard violin.

The organ player in St Hedwig played "Annum per Annum," by Pärt. I had not heard it before, but I recognized it immediately by the style. I recommend listening to both of these pieces, or anything by Arvo Pärt. It's well worth the time!

Axe of Ahneby

DESY, the Deutsches Elektronen-Synchrotron, is a national accelerator research center in Germany. I was reading a recent issue of their magazine, femto, since there were articles about supersymmetry and grand unified theories. However, those articles were really pretty boring (there's nothing much that you can say about theoretical research programs that have not accomplished anything), and my eye caught a short article near the back about the Axe of Ahneby.

Ahneby is a town in the German state of Schleswig-Holstein in the north, tucked between the Elbe river (and Hamburg) and Denmark. Several Bronze Age axes were found near this town in the 19th century, and recently, using the X-rays from one of their accelerators, DESY scientists showed that one of these axes was a fake! One of the real axes is the 4000-year-old Axe of Ahneby.

Axe of Ahneby

One of DESY's first papers, here, shows the different diffraction patterns resulting from the real axe and from a reproduction. And here is another short paper, explaining the differences.

Finally, here is a news story about the incident.

Recently on the arXiv

Some interesting papers were posted recently on the arXiv:

• Helge Kragh, a historian of physics, has a nice writeup on Robert Dicke's work on geophysics and the possibility that G might be a function of time. Dicke was a giant in the resurgence of general relativity in the 1950s and 1960s; he almost discovered the cosmic microwave background radiation; and he wrote one of my favorite textbooks: Introduction to Quantum Mechanics, by Dicke and Wittke. Even though this book was written in 1960 it has never gone to a new edition (!) because it's so perfect and concise. If you ever find a copy in a used book store, buy it.
• Kirillov and Levi describe the situation of a particle confined to a saddle - stable in one direction, unstable in the other - and show that by rotation the saddle point can be made stable.
• Several papers on Bell's theorem , quantum nonlocality, and Bell's view of nonlocality. This is always a confusing subject, and whenever I read about it I learn more, but also come up with more questions.
• Alister Graham reviews the history of black holes and how we came to believe that many galaxies (including the Milky Way) have supermassive black holes at their centers. One of the neat pieces of evidence - at least for our galaxy - is an analysis of the stars orbiting this central object. And one of the astronomers working on this problem is UCLA professor Andrea Ghez. Her website shows some cool movies.

Honorary Fellow

I am now, officially, an Honorary Fellow of the Munich University of Applied Sciences. And I'm a "Prof. Dr." Look out world!

This morning, the other visiting professor and I had a meeting with the Präsident of the University. He wanted our input on our visit, to see how the visiting fellow program could be improved in the future. It was a good meeting. Hopefully, there will be many more visiting professors, and some even visiting from Hochschule München to other places, like ERAU. I and my faculty mentor - and landlord - Karl, were there. Also, the other professor, Jack, and his mentor, Klemens, was there. Also there was the person from Int'l Programs, Nicole, who has helped us out with so many things - visas, housing, etc.

Then the group of us got our picture taken.

From left: mentor Karl Siebold, yours truly, President Michael Kortstock, Fellow "Jack" Lin, mentor Klemens Rother, International Programs representative Nicole Kewitz.

Berlin (3)

There are many churches with domes in Berlin. Along with the Reichstag Dome, which of course is not a church, there is the Berliner Dom, Deutscher Dom, and Französischer Dom, among others. Just like Alter Peter, I climbed the Französischer Dom, and got a great view of Berlin. This was the same day that I visited the Reichstag, but the pictures through that dome did not turn out as well as those that were unimpeded.

Looking east toward Alexanderplatz from the Französicher Dom. The gold-ball topped tower is the radio tower of the city and is in Alexanderplatz, the center of East Berlin. The large, low green dome in the foreground is Saint Hedwig (see next post). Note all the cranes. There was quite a bit of construction going on, which contributed to the industrial feeling.

While the sky was beautiful, the city is not as pretty as Munich. My airbnb apartment was on Alexanderstrasse, just a couple of blocks from Alexanderplatz. The area was mostly block apartment buildings, which gave the area a definite (presumably authentic) cold-war feeling. It is still worthwhile to visit, though, because of all the history that it's been through. It just doesn't feel like a small town, the way Munich does.

Bells inside Französischer Dom. Luckily, they did not ring while I was nearby. However, as I was descending the tower, they did ring. And it was quite loud. I'm glad I was not right next to them. Interestingly, there is an organ consolse visible inside the glass, and you can see the stairs to access the organ on the left. I assume that the organ player wears earplugs, especially if they also ring the bells!

Outside view of the Französischer Dom.

California Dreamin'

Caitlin and I took Kathy, Megan, and Sarah to the Flughafen early in the morning of 30.Dez to catch their 09.30 flight back to the US. It takes about 1 hour to get from Pullach to the airport by S-bahn, and because it was an international flight they had to be there early. In addition, it was cold and snowy, so the plane had to get in line for de-icing, which also takes time.

So we left Pullach at about 06.00, and Caitlin and I decided to have breakfast at the airport. We found a place that served bagels and coffee - one of the first that I had found in Munich (I have since found more), but the entire theme was California surfing. So much so that even one of the tables was inside an old VW van!

Volkswagen van at a restaurant in the Munich airport.

Table inside the Volkswagen van at a restaurant in the Munich airport. Unfortunately  we didn't notice that this was a table until after we finished eating, so we didn't get to sit there. But it was a cool idea.

After the airport, we decided to stay in town and do some museum hopping. Specifically, we went to the Munich Residenz, the city palace of the Bavarian royalty. More about that in a future post (although the number of "future posts" that I'm promising seems to be increasing more rapidly than I can write posts, so perhaps it will never happen.)

Jim Stewart (1941-2014)

The Integral House. Private residence of Jim Stewart, mathematician, textbook author.

My calculus book, handed down to me by my sister way back in 1980, was written by Earl Swokowski. I always liked that book - in fact, I still have it - and I go back and read sections of it from time to time when I need to brush up on a theorem or two. I have never been too critical about whether it was presenting proofs correctly or not. As a physicist, I usually want the answer; I'll leave the rigor to the mathematicians.

Jim Stewart also has written a calculus book, in recent years one of the best selling calculus books in the country. Now, if you write a calculus textbook, or a physics book, or chemistry, or biology, and many schools adopt that book and hundreds of thousands of undergraduates have to buy that book, well you're going to make a lot of money. Very few textbooks reach that level, however, although there are usually one or two in each field that become bestsellers. Sometimes that's because they are also classics (in the field of introductory physics, the "classics" are Sears & Zemansky, starting with their first edition right after WWII continuing to their 13th edition today, and which took  a hands-on, practical approach, and Halliday & Resnick, developed in the early 1960s, and which was decidedly more theoretical). But also it could just be that it keeps enough of everyone's favorite topic so that university textbook selection committees find it's the only one they can agree on. I don't know if this happened with Stewart's calculus book, but it has been the case (or so I suspect) with certain physics textbooks.

After making millions with his textbooks, Stewart decided to commission his home, called "Integral House," because of... who knows, his love for math? People have debated the excellence of his calculus books - see the reviews on the amazon.com page for Spivak's calculus book for a taste - but sometimes a book doesn't have to be excellent to be good.

Water

I always drink water when I am at a restaurant. In fact, I always drink water. Even if I'm drinking something else with my meal, say, a beer, I will usually drink water in addition. In US restaurants, it is customary to brink complimentary water to the table, and refill it continuously. In Germany - probably in Europe - people don't drink water in the same way.  In fact, there are no drinking fountains - zip, zilch, nada. Even at the university, Hochschule München, there are no drinking fountains. So I have learned to bring my 1-liter Nalgene bottle with me every day (filled, of course) so that I have something to drink.

In restaurants, also, they do not bring water. In fact, if you ask for water, what you are really doing is ordering a bottle of "mineral wasser." And you'll have to pay for it. And it's expensive. I knew this, but on a recent trip to a restaurant, I forgot. The first thing the waiter does is ask for your drink order (similar to the US), and when we ordered "DunklesWeissbier" (dark wheat beer) he must have asked if we wanted water. I reverted to my old, US, ways, and said yes. Of course, he brought a 750 ml bottle of Acqua Panna, which turned out to cost 5,80 EUR, more than one of the 500 ml beers, which only cost 3,60 EUR.

My advice: bring your own water when you go to a restaurant.

Bill including pizza, bier, and wasser.

Postscript. You'll notice that there is tax - it's called VAT, value-added tax - and it's 19%, which is a lot, but the tax is included in the price of the items. It's not added on at the end. This makes it very easy to calculate your bill.

Reductionism versus Emergence

Recently I attended a talk at LMU (Ludwig-Maximilians-Universität) by Gabriel Kotliar of Rutgers Univ on "Strongly correlated electron systems." It was supposed to be on superconductivity, but he widened the topic in order to discuss his approach to solid state physics, namely "Dynamic Mean Field Theory." I know what Mean Field Theory (MFT) is, it's replacing the effect of large number of nearby electrons in a solid by their average (mean) properties, and using that average to determine the effect on one electron. I don't know what the "dynamic" means. In essence, though, he was arguing for the need for a new "standard model" of solids. Band theory, Fermi liquid theory, and density functional theory have all done that job, but now something more was needed.

To make this point, he started his talk off with a bit of philosophy by quoting Dirac, who, in 1929, wrote* "The underlying physical laws necessary for the mathematical theory of a large part of physics and the whole of chemistry are thus completely known, and the difficulty lies only in the fact that the exact application of these laws leades to equations much too complicated to be soluble." This is a nice statement of the reductionist viewpoint, which holds that we currently know all the physical laws, and in principle we could calculate and explain anything that we wish. However, because of the large number of particles that make up macroscopic systems, this plan is, in practice, not possible.

Dirac continues his quote by giving a way out of this conundrum: "It therefore becomes desirable that approximate practical methods of applying quantum mechanics should be developed, which can lead to an explanation of the main features of complex atomic systems without too much computation." Presumably this is what DMFT is attempting, although Kotliar did not say so explicitly. He muddied the waters a bit by referring to a famous paper of solid-state theorist Phil Anderson, titled More is Different**, in which Anderson argues that as the number of particles increases to macroscopic size, there are features that emerge and new fundamental laws are needed to explain them. It is not possible, he argues, even in principle, to use approximations to the fundamental laws to obtain these new emergent properties. Unfortunately, Kotliar did not say which side of the debate - reductionism or emergence - he was promoting.

*Dirac makes this claim in the opening paragraph of a paper titled "Quantum Mechanics of Many-Electron Systems," published in Proc. Roy. Soc. London, Ser. A, vol. 123, pages 714-733.

**Science, 1972.

To show how difficult both quantum mechanics and the many-body problem are, there is an entire book dedicated to the Quantum mechanics of one- and two-electron atoms, by Hans Bethe and Edwin Salpeter. Two-electron atoms are an example of a "three-body problem," two electrons and a nucleus, and we really don't understand this simplest of systems completely!


Upcoming events: Two talks next week in Munich at LMU  will focus on cosmology.

• The first is a joint "public talk and discussion" by Paul Steinhardt of Princeton and Eiichiro Komatsu of the Max Planck Institute for Astrophysics. The title is "Visions of the early Universe - Sind wir Zeugen des Urknalls?" (Are we witnessing the Big Bang?). If you miss this, you can catch Steinhardt a few days later - Saturday, 31 Jan - giving the Fred Elston Memorial Lecture at the Daytona Beach campus of Embry-Riddle Aeronautical University.
• The second is the Sommerfeld Theory Colloquium at LMU given by Paolo de Bernardis of the University La Sapienza in Rome, titled "Precision Measurements of the Cosmic Microwave Background."

Reichstag Dome

The Reichstag building in Berlin, which famously burned down in 1933 and helped Hitler come to power, has a fairly new dome that is artistically elegant and scientifically useful.

Dome on the Reichstag building in Berlin, designed by Gottfried Böhm and Norman Foster.

The interior is open to visitors and is free, but you must obtain a timed pass (and you must show ID - which for me meant my passport [luckily I had it with me] - and go through and airport-style security check). There is a spiral staircase going up the inside of the dome, which allows for spectacular 360-degree views of the city. I also used an audio guide, which either was timed perfectly to my walking speed, or had some kind of location sensor that knew which side of the dome you were on so that it could point out the proper city landmarks.

The dome is directly over the Bundestag chamber, and is connected to it. That is, it is a natural heating and cooling system for the chamber, because hot air can flow up the central column and escape through the top of the dome.

Inside center of the dome. There are historical exhibits around the central "funnel," and a glass partition for visitors to peer down into the Bundestag chamber. You can also see the sun shade to the left, which rotates with the sun to keep the interior of the dome cool. Also, the outside of the central funnel, through which the air from the chamber rises, is covered in mirrors.

View of the funnel and ceiling of the Bundestag chamber from the spiral walkway. Reflections from the sky make it difficult to see down into the chamber.

View of the sun shade from the spiral walkway.

It takes about 45 minutes to read this history on the base of the dome, walk up the spiral walkway, and walk down a different spiral walkway. But it is an impressive piece of architecture. You can also walk around on the roof of the building outside the dome, from which you can also see the city of Berlin, include the River Spree (which ultimately flows into the Elbe), the Tiergarten (see here), and the Victory Column. This column used to be right outside the front of the Reichstag, and has a very interesting history, which I did not learn about when I was in Berlin, as I did not visit it, but only from Wikipedia after the fact.

Bayerische Motoren Werke AG

BMW, of course, is located in Munich. Where else would the "Bavarian Motor Works" be located? They have a plant here that produces about 1000 cars per day (!), and the entire BMW enterprise produces about 2 million cars per year. And they have a fairly stiff price - especially in Germany. It's a well-known fact (and true) that BMWs (cars in general) are cheaper in the US.

The iconic tower in a suburb north of the city center, right next door to OlympiaPark, the site of the 1972 summer Olympics. The low building in front of the tower is the BMW museum, which houses almost every model of motorcycle and automobile that BMW has built over the past 80 years. In addition, there are many Minis, which BMW has now acquired.

A car nut (or more properly "aficionado") would have a great time in the museum. I don't know enough of the history to be impressed by all the cars. There was one model, however, that I found particularly fascinating. It was the "Isetta", produced post WWII, and it had a one-cylinder (!) engine, and achieved almost 80 mpg!

BMW Isetta. Also known as a "bubble car." Notice that there are no side doors. The only "door," in fact, is the front of the car, which is hinged on the driver's side, and opens along with the steering column. It appears to be a 3 wheel car, but in fact there are two small rear wheels.

In addition to the museum, I went on a plant tour. Unfortunately, photographs were not allowed, but that was the most fascinating part. we saw the huge metal presses that stamped out pieces of the car bodies, the robots that welded these pieces together, the robots that spray painted the car bodies, the joining of the body and the transmission sub-structure, the moving assembly lines where people interacted and put the finishing touches on each car, and finally the testing area where the cars were "driven" on rollers. Quite an impressing factory. A finished car rolls off the line in about 58 seconds (on average), and the reason they only produce 1000 per day is that they are limited to two shifts because they are surrounded by residential neighborhoods (for noise control reasons).

In the section of the museum where the Minis were displayed, there were several that were larger than what I would consider a "mini." My favorite was the Mini-Limo.

Mini Limo.

Kufstein, Österreich

Yesterday I went to Oberaudorf, Deutschland, to visit the home of a colleague at Hochschule München. Specifically, it's the professor who's desk I'm sitting at. He's been out ill this entire semester, and very kindly let me use his desk. He's definitely improved, and will be back for the Sommer Semester.

He is a true Bavarian, from Oberbayern (Upper Bavaria), and is back living in the town that he grew up in. Actually, he's living in the house he grew up in. Oberaudorf is a small town of about 3,500 nestled along the left bank of the River Inn (which, of course, also flows through Innsbruck). The "foothills" of the Alps are to the West, and, of course, great skiing is just a short walk from the center of town. It's similar to Park City, Utah, in this respect: the ski lift leaves from the edge of town. So if you are a resident, all you have to do is walk a few hundred yards (or meters, if you like SI units) from your door and you're on the slopes.

We drove a short way upstream along the Inn, across the border into Austria (which is a non-event now that there's a European Union), and into the town of Kufstein. This is a slightly larger town, with about 25,000 inhabitants. There's a nice castle, which was the scene of many battles between the Bavarians and the locals several hundred years ago. And on the bridge across the Inn is a statue of Johannes von Nepomuk.

The Festung Kufstein, occupying a commanding position on a hill above the town and above the River Inn. This view is looking south (upstream toward Innsbruck).

Johannes von Nepomuk is a national saint of the Czech Republic, who was drowned in the Vltava river at the behest of Wenceslaus, King of the Romans and King of Bohemia. (Wikipedia)

Berlin Wall (2)

An interesting perspective that I had never thought of before, was how did the GDR deal with fact that the underground trains crisscrossed Berlin, and even if the Wall prevented passage above ground, there was a network of tunnels ready made to serve the potential escapee.

An entrance to the S-bahn near Brandenburger Tor after the war. Today, the U-bahn is the "underground" network of trains that Americans would call the "subway," and the S-bahn is the "suburban" network of trains that usually runs above ground, although in the inner city (of both Munich and Berlin) they must also travel underground. At the far end of the building on the right is the location of the Starbuck's today.

 As the Wall got stricter and stricter, they had to essentially split the subway systems into two different networks, so that you could not simply take the subway to escape from East Berlin. However, a few of the West Berlin subway lines actually ran underneath East Berlin territory, where in addition there were stations! These stations were closed, of course, and they came to be known as "ghost stations," because the trains would only slow down in these stations, but not stop. In addition, they were manned by East German police, to make sure, presumably, that no East Germans tried to hop on, but also that no West Germans tried to hop off.

Several of the successful (and unsuccessful) escapees used the underground tunnels.

Here is a view of the same station, now an U-bahn station, near Brandenburger Tor, taken on 4 Jan 2015, by yours truly. In fact, there is also an S-bahn station, but that has a separate entrance. Notice the new buildings to the left of the Tor. The large white one is the United States Embassy. The area is much less desolate than in the previous photograph.

Mr. Gorbachev, tear down this wall!

Definitely one of the most impressive places to visit in Berlin is the Berlin wall.  Of course, the wall existed throughout the city, and most of it is commemorated by stones in the ground, crossing streets, sidewalks, buildings.

A piece of the Berlin wall in Potsdamer Platz. This was one of Germany's busiest intersections between the two Great Wars. But after the wall went up, it became a ghost town.

The wall passed just to the west of the famous Brandenburger Tor (see the next post), which was where Reagan made his famous speech. There is, however, an official Berlin Wall memorial site, that has preserved several blocks of the "death strip" (the no-man's land between two walls) and a block of the wall itself.

Portion of the Wall along Bernaer Straße, site of the Gedenkstätte Berliner Mauer (Berlin Wall memorial site).

View of the wall and the "death strip" along Bernauer Straße  from the roof of the museum building across the street.

One of the things I found interesting was the fact that in the building up of the wall over the years, increasing the security, an entire church was caught in no-man's-land. Ironically, it was the Church of Reconciliation. The following photo shows the rapid change to the wall near the church site.

Evolution of the wall near the Church of Reconciliation.

In 1985, the church was demolished, but after the wall fell, another building was erected on the original site, and it can be seen toward the left in the panorama above.

It's a powerful experience to just walk around the area. Even though it is gone, the feeling one gets is not describable.

More graves in Berlin

While in Berlin, I couldn't help but looking for more famous physicists. And in this case, I got a mathematician, too. I went to the St Matthäus Kirchhof where Gustav Kirchhof, of Kirchhof's Laws (both electrical and thermodynamic) is buried. I was a little confused as to why the cemetery had the same name as the person, but Kirchhof just means 'churchyard', so it was the St Matthäus churchyard cemetery. Unfortunately, I never found Kirchhof's grave, so you'll have to be content with a photo of the impressive entrance arch.

Entrance to the St Matthäus Kirchhof cemetery.

I did, however, find Leopold Kronecker's grave, along with his wife, Fanni. Kronecker, was a 19th century mathematician who is credited with the quote, "God made the integers, all else is the work of man." In physics his name often comes up in reference to the Kronecker delta symbol, δ_ij, where the subscripts i and j typically take on the integer values 1, 2, 3, and the value of the Kronecker delta is equal to 1 if i = j, and is equal to 0 if they are not equal. 

Grave site of Leopold Kronecker, mathematician

Kronecker is also related to me academically (or rather I am related to him). If you go to the Mathematics Genealogy project, the picture of the "tree" shows Dirichlet, who was Kronecker's advisor. I, on the other hand, am "descended" from Dirichlet through Lipschutz, Klein, Lindemann, and Sommerfeld.

Haydn, Mozart, Beethoven

In the Berlin Tiergarten there are many statues. One that I found that was particularly nice was this one.

This is the Haydn-Mozart-Beethoven monument. It apparently had a troubled history, especially during WWII. It has since been moved and refurbished, although you can still see bullet holes in the closeup shots. 

It's a three-sided monument, with a sculpture of one composer on each side. Your task is to determine who is who? The first one to guess correctly in the comment section wins a prize!!

Number 1.

Number 2.

Number 3.

The names are carved on the monument, but I think the resolution that I've posted is not high enough for you to read them, even if you download the jpg files and zoom in. In any case, that would be cheating! So, you are allowed to zoom in on the faces, but that is all. Good luck.

Berlin - day 1

I arrived Friday night after a short flight (on Air Berlin, naturally) from Munich. The Germans were a little more pushy exiting the plane than I'm used to. But that's pretty typical. When entering or exiting trains, for example, it's not typical for them to defer to those around them, but just to move and exit first. Just another cultural difference. And another difference - one of the snacks offered was lebkuchen! It's everywhere (more on that on day 2).

In any case, I successfully found the bus (TXL) heading to Alexanderplatz, paid and got on. My first impression is that is is more stark and industrial than Munich, and also dirtier. That was confirmed when I got out and about - see photos in the next few posts. Also, it turns out that Berlin has two airports (who knew?), and I landed at Tegel, which is a bit closer to the center of town, also known as "Mitte."

My airbnb home is in an apartment building in Mitte, smack in the East Berlin section of town. I don't know how many of the buildings remain from that period, but this area definitely has a Soviet feel to it.

So here are a few photos from my first day

The famous Brandenburger Tor.

The only gate of the old city left standing, and it attracts all visitors, even Napoleon.

The Reichstag.

It's been rebuilt several times, and only the facade and four towers (one on each corner) are left from the original. The four towers represent the four kingdoms Prussia, Bavaria, Saxony, and Würtemburg, that the unified Germany, well, unified, in 1871. Of course, this is the building that burned down in 1933, which propelled Hitler and the Nazis toward absolute power.

A statue of an Amazon on a horse in the Tiergarten, a large park adjacent to the Brandenburger Tor that was originally a royal hunting ground. It is now the largest public park in Berlin. I walked a bit in the park. It is very nice, but not as nice as the Englischer Garten in München. You'll notice a theme among my comments on Berlin - nice, but not as nice as Munich.

Next post: guess the famous composer! (12 noon PST)

Happy 2015!

To celebrate, here's a photo of the famous Neues Rathaus in the snow (well, the glockenspiel is famous) in Marienplatz (which is also the famous site of the Munich Christmas Market), as viewed from the top of Alter Peter (not so famous), a nearby kirche which can be climbed.

And here is a wider panorama that shows the Frauenkirche (the two towers on the left), as well as more of Munich, including the Residenz (the main Palace of the ruling Bavarian monarchy for a long time - at least until they were deposed in 1918) in the distance on the right (more about this building in a later post).

The snow is about 2 feet deep, as it has been snowing since December 26, although it did not snow yesterday, nor has it snowed today yet. It doesn't look like it will, and the temperature is supposed to climb over the next few days, so I'm guessing that some of it might melt.

Have a healthy and productive 2015, or as Garrison Keillor says, "Be well, do good work, and keep in touch."