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.