Cathedrals old and new (wherein Connie explains physics)

The other highlights of our trip in Geneva were visiting the Cathedrale Saint-Pierre and CERN. First things first, we walked downtown from our apartment (about a 30 minute trip) to the old city in Geneva and got lunch en route (Bolivian food for once!). We reached the Cathedrale Saint-Pierre after going through some passages. Downtown Geneva is made of a bunch of hills, but over the centuries, they’ve been scraped down some and removed in other places or just tunneled through so that they fit in more or less with the street structure. That does mean sometimes there are two levels of streets or roads. Some of these passages are closed most of the year, but we came up one that emerged just behind the church. The cathedral itself is interesting because it was a Gothic cathedral built in the 1500s, but during the Reformation, it became a Protestant church removed of all the gilt, icons, rood screens, and art that Catholic cathedrals are well known for. Inside, you can even see a few examples of where stone carvings are defaced and cracked. (I’m guessing they took that second commandment real seriously.) The only thing that’s left are the rose windows and stained glass windows. The Cathedrale Saint-Pierre is known for being the church of John Calvin, who preached at the church literally thousands of times. There was one wooden chair known for being Calvin’s chair in the building, and it seemed kind of small, but then, as Steve remarked, they were all smaller back then.

We paid 5 CHF each to climb the tower to the top of the cathedral. It was a gorgeous view in all four directions. To the east, we could see over Lac Leman where the Jet d’Eau comes out. To the south is Salève the mountain and France. It’s apparently the shortest mountain (or something that could be called a mountain) in France, but looming way behind it is Mont Blanc in France, the tallest mountain in Europe. To the north and west are the Jura Mountains/ national park in France, which are also quite tall and form a solid barrier of sorts. So Geneva looks quite closed off for that reason. After we checked out the cathedral, we walked around the Jardin Anglais which is downtown by the lake. There were public pianos around, which some people kept playing tracks from Amélie on (just in case you forgot you were in the French part of Switzerland), and it was a lovely sunlit afternoon. We walked home afterwards.

One last thing about Sunday: Switzerland is very trying on Sundays. That’s because absolutely nothing is open. Pretty much all the supermarkets and normal stores are closed on that day, and it’s very sleepy indeed. The church was probably the only thing we could count on being open. I was definitely kind of disgruntled that we were not able to visit the Coop to buy presents and groceries, and probably the only person around who really wished for Monday to come faster.

On Monday itself, we got up early and took the nearby tram 18 all the way to its end at CERN. I had almost forgotten CERN was here when we booked our trip to Geneva. Thankfully, a friend who is doing his post-doc there asked if we wanted a tour, and we were very glad to accept. CERN is the European Organization for Nuclear Research, established in 1954. It’s more appropriate to call it the European laboratory for particle physics these days, since that’s what CERN has been concerned with since then. It is presently the home of the Large Hadron Collider (LHC), which is a 27-kilometer long circular tunnel where particle beams are collided at high speeds to simulate what the world looked like closer to the Big Bang. That’s the 5-second explanation. In reality, what we learned about was much more complicated but also more interesting.

When we got to CERN, Max guided us through a good two hours of walking around and looking at exhibits and actual colliders. The Micocosm exhibit at CERN was actually really great and did an excellent job of explaining the science behind the collider and its experiments. For example, one of the first things Max showed us was a super-saturated cloud exhibit through which you could actually see the trails left behind by muons and alpha particles as they actually passed through our bodies and everything else on earth at that time. These particles would knock electrons out of the atoms in their way, leaving a little trail. It’s impossible to see these things, but if you know how to do it, their trail is detectable. We also learned about how to accelerate the particles: the particles go round and round smaller circuits, and each time they go through an accelerator unit, the electromagnetic field is flipped at just the right time so that they give the particles a boost, and if it’s timed well, then with enough time and circuits, you can accelerate the particles up to what they need to be before they get sent into the collider. So what Max showed us were circles upon circles, smaller ones feeding into the larger ones.

What makes the LHC and the other colliders even more complex is the implications of how to maintain a circular collider and how to detect collisions. First, magnets are the tools of choice to bend the particles’ path so that a circular (and thus viable) collider can be built, so there are an incredible number of magnets wrapped around the entire collider. Also, at very low temperatures (2 Kelvin), the magnets are superconducting, which means they can operate at absolute efficiency, or no loss of energy, so there’s liquid helium piped in around the entire collider to keep it even colder than outer space (which is around 2.7 Kelvins). So now you have an operating collider… what’s next? Well, you have to detect the collisions in the first place. LHC is the place where CERN scientists concluded they had been able to generate the Higgs Boson, a heavy particle which decayed to a trail of four muons (and some other stuff, but let’s just say this to be simple). They were able to conclude that because the muons and other particles were detected in the layers all around the actual collider beams. That requires many layers of silicon and other materials layered just so, so that the muons and other particles will knock out electrons in the sheet of silicon, and by comparing the path it took to knock out electrons in multiple sheets layered on top of each other, we know how fast it was traveling and what kind of particle it was likely to be. This generates an immense amount of data; when the beam is running, there’s a collision every 25 microseconds, and each collision generates about a megabyte of data. So every second, a gigabyte accumulates. Of course, they don’t save all of it – thanks to the models and simulations, they have a good understanding of what is likely to mean an abnormal path or collision which indicates they may have an interesting looking collision on their hands, and so anything above a certain threshold is saved. That’s why Max quipped that CERN actually started Big Data as a trend. It’s certainly the largest dataset in science, even if it isn’t the largest repository of data in the world anymore (thanks Google and Amazon Web Services).

After being briefed on the physics, we were ready to see the real deal. First, Max took us out to the sculpture garden, which features machines that used to be in use at CERN and now are just art. One in particular looked like a silvery domed structure about to take off. However, it and the piston which filled it (also lying nearby) were actually old particle accelerators from the 1970s. There was also a copper one which looked especially beautiful. Next, we went to the Low Energy Ion Ring (LEIR), an actual accelerator responsible for speeding up lead ions. Max brought us inside this huge warehouse-factory floor combo structure, and was able to show us the space where they were prototyping accelerator parts as well as where the LEIR was located. I think part of what surprised me about this facility at CERN was how old it was. We’ve all heard about the Large Hadron Collider, and maybe assumed everything around it was shiny new. But CERN’s been around since the 1950s, and many of the facilities have been used and reused since then to accelerate and collide new things. The LEIR was actually fairly small, less than 50 meters in diameter, and resembling more of a rounded square than a circle, and only operated a month or two out of the year when they wanted to do an injection of the lead ions. According to the history of the machine, it was actually updated from an even older machine from 1993 which originally accelerated anti-protons.

Our minds still reeling from all the science, we went off for lunch nearby. Like many campuses, CERN maintains its own restaurants and canteens, and this one was absolutely delicious. There were many CERN employees as well as the odd visitor or two. I got an amazing veggie buffet dish and also a slice of amazing looking chocolate pear tart (which did turn out to be the most delicious thing), and we caught up on each other’s lives as well as more about life in Geneva. It was a wonderful visit in all, and I’m really glad we had this opportunity.

Finally, I wanted to explain the title. Steve insisted that this entry be entitled “Cathedrals, old and new”, because of how complex and large the particle accelerators are. The next, larger accelerator at CERN will be 100 km in length, four times the length of the LHC, and will take until 2060 to finish. In that, it is not unlike the cathedrals in the past, which took an incredibly long time to complete, but held a central place of importance in people’s lives. It is daunting to think about how long it will take until the next particle accelerator is finished. It is truly one of the engineering projects on earth that we can be reasonably sure will take our lifetime to complete and come to fruition.

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