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Aidan Randle-Conde | Université Libre de Bruxelles | Belgium

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Lab news

Friday, April 1st, 2016

Get the latest news from the world’s biggest science lab! All the facts, all the truth, totally verified and true beyond all reasonable doubt. 85% official news. Brought to you by the team that revealed Elvis landing on the moon.

ATLAS to install neutrino calorimeters

The ATLAS detector is currently the largest experiment on the CERN site, weighing over 7,000 tonnes, spanning 50 m across and almost 50 m long. It can detect nearly all particles produced in the record breaking high energy collisions provided by the LHC. These particles have strange names like the electron, proton, pion, Ξ(1530)3/2+, photon, friton, demi-semi-lepton and Boris. But there is a big problem, which becomes more pressing as we reach higher and higher energies, and that is the neutrino. This is a tiny, neutral, almost massless particle that was predicted in 1930, and it comes in different flavours (the most popular being mint.) The ATLAS Collaboration has an ambitious plan to extend the capabilities of its detector by being the first such general purpose detector to install neutrino calorimeters. At the moment a neutrino is seen as “missing transverse energy”, and that makes it really hard to find new particles.

ATLAS Spokesperson, Dave Charlton, said “Look I really don’t have time for this, I have to go to a meeting!”. After reporters blocked his path and stole his CERN card he added “Fine, how about ‘This is a very exciting time for ATLAS and we are happy to be leading the field in this area. Detecting neutrinos will open up new parameter space and allow to perform searches never seen before.’ Now give me my CERN card, the Weekly meeting cannot start without me.” By seeing neutrinos directly, physicists would be able to observe the annoying neutrino backgrounds that get in the way of dark matter searches. They could count the neutrinos directly to see if they agree with long standing predictions.

Proposals for the new ATLAS neutrino calorimeters

Proposals for the new ATLAS neutrino calorimeters

But not everyone is happy with the proposal. We spoke to a neutrino expert, and after she closed the door on us, we went to Wikipedia. Apparently neutrinos are so bad at interacting that they need about one light years of lead before they can be seen. This would have some impact on the local (and not so local) area. We spoke with a representative from Geneva Airport. He said “If the proposed plans are succesful this would mean moving Geneva Airport. The people and businesses of Geneva rely on the airport for connections with the rest of the world. It would be very inconvenient and not very efficient to commute a light year to reach the airport. Most rental car contracts will not allow you travel that far.”

It’s not yet clear where the supply of lead will come from. A sphere of solid lead would contain more than the global supply, even if every atom was liberated from the Earth’s crust. We would need 38 orders of magnitude more than there is on the planet. That’s more than a million million million. It’s lots. There is also a problem with the sheer size of the proposal. “There are problems we still have to solve”, said an ATLAS physicist “We have a Solar Passage Working Group, and NASA is helping us deal with other local astronomical bodies that might pose impact challenges. Trigger is an issue. Right now it takes about 100 milliseconds to trigger an event. With the new neutrino calorimeters it could take up to 3 years.”

The proposals, if approved, will be implemented by 2600.

CMS developing “truth matching” for data

For decades the CMS Collaboration has used a common tool known as “truth matching” with its simulation studies. Every particle in a simulation has information associated with it, including its mass, energy, charge, momentum, spin, and favourite movies. All these quantities have to be estimated using measurements from the simulated detector, so they are never perfectly known. However with a simulation you can match up the particles to what really happened with the so-called “truth record”, and this is what we call truth matching. If you have a particle travelling with a certain momentum in a certain direction you can compare it to the truth record and find out exactly what kind of particle it is. That means you no longer need those tricky identification algorithms, and you can remove background processes trivially.

“This makes my analysis super easy!” said one CMS student. “I might even graduate next week.” Truth matching has been applied to simulations for several decades, and it it is unique in being the only method that has not also been applied to data. Everything else, from machine learning to Bayesian analysis, have been developed using simulation before being moved over to real data. By employing ouija boards, dowsing techniques, and Feng Shui, CMS psychics have reported initial success. “There are definitely a lot of protons in the LHC beam.” one said. The LHC beam does indeed contain about a million million protons per bunch, and this has been seen by some as a sign of confirmation of the method. Others are more skeptical. “Those protons could have come from the magnets or the pipes. There’s a lot of matter in these tunnels. The results prove nothing.”

One of the first complete data events to be truth matched, a diphoton Higgs decay

One of the first complete data events to be truth matched, a diphoton Higgs decay

If the truth matching of data is successful, it could lead to a revolution in particle physics. Detectors could be slimmed down, time could be saved in the analysis process, and the peer review process would be streamlined. “Rather than having to measure the levels of signal and background, a process that can take months, we can simply count how many electrons bosons we have.” The initial findings are only the first step, and there are plans to extend the data truth matching to more complex final states. It’s expected that by 2019 the CMS Collaboration will be able to truthmatch Higgs bosons, top quarks, and even new particles we’ve never seen before.

A tearful Polish professor, who pioneered the use of the famous ‘pseudorapidity’ variable said “I have been waiting for this breakthrough my entire career. This will make the lives of so many scientists so much simpler.”

LHCb made a big blunder, and you won’t believe what it is!

Senior LHCb physicists were left red faced today when they discovered a terrible blunder. “How could we not have seen this?” Spokesperson Guy Wilkinson said. “It’s been staring us in the face for years” blurted Operations Coordinator Barbara Storaci.

LHCb, a huge science machine that lives underground on the Franco-Swiss border, is hiding a huge secret. Sources on reddit tell us “This kind of hting happens al the time. The Eiffel Tower was bilt up-side-down for the frist few weeks.” and “OMG! WTF? ORLY?”

Can you see what’s wrong with this picture? 98% of people can’t!

The LHCb schematic, with the approved geometry

The LHCb schematic, with the approved geometry

It turns out that when LHCb was made, the engineers only built half a detector. “Now I see it I can’t unsee it!” exclaimed a postdoc, spilling crepe on the table as he spoke.

“It may be true that we only built half a detector”, an anonymous researcher said “but at least it was the forward half.” So far there are no plans to correct the problem, and the Collaboration has already produced hundreds of world class papers with the current detector and shows no signs of stopping.

ALICE alchemists quit after years of research

A team of alchemists working on the ALICE Collaboration have today announced that their research program will end today. The collection of six pesudoscientists, a small minority of the total Collaboration, are hanging up their lab coats after declaring their research “unworkable” and “a total abysmal failure”. The ALICE Collaboration investigates the collisions of Lead ions with other particles in the LHC. The Collaboration has been responsible for a wide range of discoveries concerning the quark-gluon plasma, which is a form of primordial matter from the early universe.

The STAR experiment contained real Gold atoms

The STAR experiment contained real Gold atoms

However it is not the quark-gluon plasma that the small band of alchemists are studying. Instead they want to turn the Lead into Gold, and they want to use the LHC to do it. Most of them came from the previous generation of ion collider experiments, based in Brookhaven, New York. At those facilities there was an abundance of Gold in the experimental apparatus, and it the alchemists looked to replicate this success.

“I just don’t understand” said Bob Bobbatrop, the Master Mage “we had so much success with the RHIC accelerator! The LHC must be producing negative energy fields and the crystals in our detector must be misaligned.” ALICE Spokesperson, Paolo Giubellino, was quick to distance himself from the misfit alchemists. “They are not representative of the Collaboration as a whole, and frankly, I don’t know how they got in here in the first place. The RHIC facility in Brookhaven collided Gold ions, so of course these so-called alchemists found Gold. They’d have to be even stupider not to find it there! This is why we have a peer review process. We’ve even started to arrange psuedomeetings in a local coffee shop where they present their results, and they haven’t yet noticed that most of the people listening are tourists. Even the local barista rolls her eyes when they talk. Meanwhile we can get on with the real research.”

But like a gauge violating wavefunction, Bob Bobbatrop is not phased. “We have vastly superior software! When we need a random number we don’t rely on a C++ library, we use a 20 sided die. You can’t get more serious than that.”

Cryogenics team start charity drive

Do you have any old, unwanted fridge magnets? You can send them to CERN! Last year the cryogenics team at CERN faced problems that lead to the failure of some magnets. Now, a charity drive is starting where you can donate your old magnets, and these will be attached to the outside of failing magnets to give them a boost. “We accept any magnets! That magnet you purchased on vacation? Yes, we’ll take it. Do you have magnetic letters? We will take those too.”

Donated magnets in the staging and testing area

Donated magnets in the staging and testing area

Some magnets are more useful than others. Magnets with mini thermometers can help engineers keep track of the state of the supercooled LHC magnets. The resident artists at CERN have expressed an interest in the magnetic “fridge poetry” packs. Magnets that feature cats will be used in the RF cavity sector. So please, take a look at your fridge, and see if you really need that snow globe magnet from Oslo, or that hula girl magnet from Hawai’i. Why leave it sitting in your kitchen when it can be helping research on the world’s largest machine?

Creative solution to poster defacement row

In recent weeks the media has reported on defacement of the LGBT CERN posters at the lab, with many being removed or subject to grafitti. CERN Director General, Fabiola Gianotti, has taken these incidents very seriously. “The targeting of a single group of posters for abuse like this unacceptable” she said, “and so I have made the decision that from now on, all types posters at CERN will be removed or defaced. CERN is a lab of equal opportunities, and it must be free from discrimination.”

Teams of administrators, including Gianotta herself, have been seen walking the corridors of CERN and instituting this new policy. Posters announcing a SUSY conference have had “NO MORE SYMMTRY BRAKING HERE!!1!” scrawled across them, and a poster advertising a symposium on solar neutrinos was subjected to “Go back to where you came from. The sun.” written on it. Even parking signs are not immune, with slogans such as “Parking? More like… splarking!” and a fire exit sign was seen with a neatly written note underneath saying “They had fire in Hitler’s Germany too, you know”.

One of the many posters subject to the new policy

One of the many posters subject to the new policy

By attacking all signs and posters at the lab, the aim is to make nobody feel victimised or isolated. Staff are encouraged to use their own initiative and are recommended to mutter incoherently under their breath as they do so. “If nothing else” one technician said “it’s made the lab more surreal. I don’t even know how much a coffee is anymore. Apparently it’s now one ‘WHY ARE YOU READING THIS?!’, but it used to be 1.60 CHF.”

LIGO result explained

In February 2016, the LIGO experiment announced it had observed gravitational waves, predicted over a century ago by Albert Einstein’s theory of general relativity. The discovery is thought to have come from the merging of two massive black holes, from over a billion light years away. However, two students have come forward to say that they created the waves in their apartment, using a waffle iron, an iPhone, and the cluck of a chicken. “We’ve been working on this prank for weeks” said the first student, “and we had no idea it would be taken seriously!” The second student added “We had to eat so many Pringles to get enough tubes for the wave generator.”

Captain McNuggets, relaxing in the garden

Captain McNuggets, relaxing in the garden

The real hero of the story is their chicken, Captain McNuggets, who made the characteristic “chirp” sound. So did LIGO really detect gravitational waves? “Oh, absolutely!” the pair of students replied. The machine they made could produce gravitational waves of any frequency and amplitude desired, but it was only made “for a bit of a laugh” and is unlikely to see further research. The machine itself was dismantled in October to make space for their latest project, the “ballistic taco-launcher”.


LHC Run 2 cancelled, CERN closes doors

Wednesday, April 1st, 2015

After a three week review CERN Director General, Rolf Dieter Heuer has announced that the LHC will not have another run and that the international laboratory will be closing its doors to science. The revelation follows an intense week of discussion, analysis and rumour mongering.

While deleting some old files from the myriad of hard drives at the CERN Computing Centre, IT support found some data nobody had seen before. “It was just sitting there on a few hard drives in the corner” said Linus Distro, from IT Support. “So I told the analysts to take a look at it and the rest is history!”

The single event that definitely proved the existence of supersymmetry (BBC)

The single event that definitely proved the existence of supersymmetry (BBC)

It turns out the rest is history, because these few exobytes of data held the answers to all of the open questions of physics. After discovering a staggering 327 new particles the physicists managed to prove the existence of supersymmetry, extra-dimensions, dark matter, micro black holes, technicolor, and top quark condendsates. But not string theory, that’s just silly.

Theorist John Ellis commented “I never thought I’d see this in my lifetime. I mean, I expected to see supersymmetry and dark matter, but now we have technicolor too. It’s quite simply amazing. We’ve been sitting on this data for years without even knowing it.”

Due to take on the role of Director General in 2016, Fabiola Gianotti said “Now that physics is finished I’m not sure what to do. I was expecting a long and industrious career at the lab, now I can retire early and buy a nice beach house near Napoli.”

The situation for unviersitities across the world is less clear. PhD students are expected to have up to seven theses each to cope with all the extra discoveries. Professors are starting to panic, trying to save as much of their funding as possible. There has been a sudden increase in the number of conferences in Hawai’i, Cuba, and the Bahamas, as postdocs squeeze as much opportunity out of the final weeks of their careers as possible.

The ALICE Control Room will be repurposed into a massive Call of Duty multiplayer facilitiy (ALICE Matters)

The ALICE Control Room will be repurposed into a massive Call of Duty multiplayer facilitiy (ALICE Matters)

“The atmosphere on site is incredible!” shouted one slightly inebriated physicist, “People say we should measure everything down to the 6th decimal place, but to be honest we’ll probably just stop after four.”

Famous atheist Richard Dawkins as leapt on the opportunity to prove the non existence of god. “If those files answer all the questions physics has left then surely it proves there is no god.” he tweeted last week. And he’s not alone. Thousands of people across the globe are finally realising that with no questions left to answer, they are completely intellectually and spiritually satisfied for the first time in history, and are busy validating their own world views.

Among the top answers are the following: Schrödinger’s cat is alive and well and living in Droitwich, god plays dice on Tuesdays, light is a particle and a wave and Canadian (and hopes you’re having a good day), electrons are strawberry flavoured, Leibniz and Newton were good friend who discovered calculus together, and if you could ride a beam of light it would be totally freaking awesome.

While the phycisists may not have much to do anymore the number of visitors has increased by a factor 3500% in the past two weeks. People from all over the world are descending upon CERN to experience extra dimensions and parallel universes. For 20 CHF a family can visit a parallel universe of their choosing for up to two weeks. Head of CERN Visits Mick Storr said “It’s a great time to visit CERN. Finally we know where we came from, where we’re going, and what we’re made of. Now I just need to work out what to have for dinner.”

Early crowds grather to see the creation of the daily 14:00 wormhole at CMS. (CERN)

Early crowds grather to see the creation of the daily 14:00 wormhole at CMS. (CERN)

It’s unclear what will happen next. There are certainly questions about how best to use the extra dimensions, but the biggest problem is a social one. Nobody knows what will happen to the thousands of physicists who will have to re-enter the “real world”. It’s a scary place for some, and physicists lack basic transferable skills such as burger flipping and riot control.

Whatever happens, everyone will look back at the Winter of 2015 as most exciting year in science history. This year’s Nobel Prize ceremony will be a complicated matter indeed.


30 reasons why you shouldn’t be a particle physicist

Monday, March 2nd, 2015

1. Some people think that physics is exciting.



2. They say “There’s nothing like the thrill of discovery”.

(ALICE Masterclass)

(ALICE Masterclass)

3. But that feeling won’t prepare you for the real world.



4. Discoveries only happen once. Do you really want to be in the room when they happen?



5. It’s not as though people queue overnight for the big discoveries.



6. CERN’s one of the biggest labs in the world. It’s like Disneyland, but for physicists.

7. The machines are among the most complex in the world.

(Francois Becler)

(Francois Becler)

8. Seriously, don’t mess with those machines.



9. They’re not even nice to look at.

(Michael Hoch, Maximilien Brice)

(Michael Hoch, Maximilien Brice)

10. The machines are so big you have to drive through the French countryside to get from one side to the other.

11. There’s nothing beautiful about the French countryside.

12. And there’s nothing cool about working on the world’s biggest computing grid with some of most powerful supercomputers ever created.



13. A dataset so big you can’t fit it all in one place? Please.



14. So you can do your analysis from anywhere in the world? Lame!

(CERN Courier)

(CERN Courier)

15. And our conferences always take place in strange places.

16. Who has time to travel?

17. Some people even take time away from the lab to go skiing.



18. Physicists have been working on this stuff for decades. Nobody remembers any of these people:



19. But particle physics is only about understanding the universe on the most fundamental level.

20. We don’t even have a well stocked library to help us when things get tough.

21. Or professors and experts to explain things to us.

22. And the public don’t care about what we do.



23. Even the press don’t pay any attention.

(Sean Treacy)

(Sean Treacy)

24. And who wants to contribute to the sum of human knowledge anyway?



25. There’s nothing exciting about being on shift in the Control Room either.



26. Or travelling the world to collaborate.

27. Or meeting hundreds of people, each with their own story and background.

28. You never get to meet any interesting people.



29. And physicists have no sense of humour.

30. Honestly, who would want to be a physicist?




  • http://www.atlas.ch/news/2008/first-beam-and-event.html
  • http://opendata.cern.ch/collection/ALICE-Learning-Resources
  • http://cds.cern.ch/record/1406060?ln=en
  • http://cds.cern.ch/record/1459634
  • http://cds.cern.ch/record/1459503?ln=en
  • http://cds.cern.ch/record/1474902/files/
  • https://cds.cern.ch/record/1643071/
  • http://cds.cern.ch/record/1436153?ln=en
  • http://home.web.cern.ch/about/computing
  • http://home.web.cern.ch/about/computing/grid-software-middleware-hardware
  • http://cerncourier.com/cws/article/cern/52744
  • http://lhcb.web.cern.ch/lhcb/fun/FunNewPage/album-crozet-jan2012/index.html
  • http://en.wikipedia.org/wiki/Solvay_Conference
  • http://home.web.cern.ch/about/updates/2014/05/cern-celebrates-its-anniversary-its-neighbours
  • https://atlas-service-enews.web.cern.ch/atlas-service-enews/2009/news_09/news_beam09.php
  • http://the-sieve.com/2012/07/06/higgsmania/
  • http://www.stfc.ac.uk/imagelibrary/displayImage.aspx?p=593
  • http://press.highenergyphysicsmedia.com/ichep-2012-cern-announcment.html
  • http://cds.cern.ch/record/1965972?ln=en
  • http://cds.cern.ch/record/1363014/

Finding tomorrow’s scientists

Tuesday, September 2nd, 2014

Last week I was at a family reunion where I had the chance to talk to one of my more distant relations, Calvin. At 10 years old he seems to know more about particle physics and cosmology than most adults I know. We spent a couple of hours talking about the LHC, the big bang, trying to solve the energy crisis, and even the role of women in science . It turns out that Calvin had wanted to speak with a real scientist for quite a while, so I agreed to have a chat next time I was in the area. To be honest when I first agreed I was rolling my eyes at the prospect. I’ve had so many parents tell me about their children who are “into science” only to find out that they merely watch Mythbusters, or enjoyed reading a book about dinosaurs. However when I spoke to Calvin I found he had huge concentration and insight for someone of his age, and that he was enthusiastically curious about physics to the point where I felt he would never tire of the subject. Each question would lead to another, in the meantime he’d wait patiently for the answer, giving the discussion his full attention. He seemed content with the idea that we don’t have answers to some of these questions yet, or that it can take decades for someone to understand just one of the answers properly. The road to being a scientist is a long one and you’ve got to really want it and work hard to get there, and Calvin has what it takes.

Real scientists don't merely observe, they don't merely interact, they create.  (Child at the Science Museum London, studying an optical exhibit.  Nevit Dilmen 2008)

Real scientists don’t merely observe, they don’t merely interact, they create. (Child at the Science Museum London, studying an optical exhibit. Nevit Dilmen 2008)

Next month Calvin will start his final year in primary school and his teacher will be the same teacher I had at that age, Mark (a great name for a teacher!) From an early age I was fascinated by mathematics and computation, and without Mark I would not have discovered how much fun it was to play with numbers and shapes, something I’ve enjoyed ever since. Without his influence I probably would not have chosen to be a scientist. So once I found out Mark was going to teach Calvin I got in touch and told him that Calvin had the spark within him to get to university, but only if he had the right help along the way. In the area we are from, an industrial town in the North West of England, it is not usual for children to go to university, and there’s often strong peer pressure to not study hard. In this kind of environment it’s important to give encouragement to the children who can do well in academia. (Of course it would be better to change the environments in schools, but changing attitudes and cultures takes decades.)

All this made me think about my own experiences on the way to university, and I’m sure everyone had their own memories of the teachers who inspired them, and the frustrations of how much of high school focuses on learning facts instead of critical thinking. At primary school I had exhausted the mathematics textbooks very early on, under the guidance of Maggie Miller. From there Mark took over and taught me puzzles that went beyond anything I was taught in maths classes at high school. It was unfortunate that I was assigned a rather uninspiring maths teacher who would struggle to understand what I said at times, and it took the school about four years to organise classes that stretched its top students. This was mostly a matter of finding the resources than anything else; the school was caught in the middle of a regional educational crisis, and five small schools were fighting to stay open in a region that could only support four larger schools. One of the schools had to close and that would mean a huge upheaval for everyone. Challenging the brightest students became one of the ways that the school could show its worth and boost its statistics, so the pupils and school worked together to improve both their prospects. Since then the school has encouraged pupils to on extra subjects and exams if they want to, and I’m glad to stay that not only has it stayed open but it’s now going from strength to strength, and I’m glad to have played a very small part in that success.

By the time I was at college there was a whole new level of possibilities, as they had teams dedicated to helping students get to university, and some classes were arranged to fit around the few students that needed them, rather than the other way around. Some of the support still depended on individuals putting in extra effort though, including staff pulling strings to arrange a visit to Oxford where we met with tutors and professors who could give us practice interviews. I realised there was quite a coincidence, because one of the people who gave a practice interview, Bobbie Miller, was the son of Maggie Miller, one of my primary school teachers. At the same time one of my older and more dedicated tutors, Lance, had to take time off for ill health. He invited me and two others over to his house in the evenings for extra maths lessons, some of which went far beyond the scope of the syllabus and instead explored critical and creative mathematical thinking to give us a much deeper understanding of what we were studying. After one of my exams I heard the sad news that he’d passed away, but we knew that he was confident of our success and all three of us got the university positions we wanted, largely thanks to his help.

Unable to thank Lance, I went to visit Maggie Miller and thanked her. It was a surreal experience to go into her classroom and see how small the tables and chairs were, but it brings me back to the main point. Finding tomorrow’s scientists means identifying and encouraging them from an early age. The journey from primary school to university is long, hard, full of distractions and it’s easy to become unmotivated. It’s only through the help of dozens of people putting in extra effort that I got to where I am today, and I’m going to do what I can to help Calvin have the same opportunities. Looking back I am of course very grateful for this, but I also shudder to think of all the pupils who weren’t so lucky, and never got a chance to stretch their intellectual muscles. It doesn’t benefit anyone to let these children fall through the cracks of the educational system simply because it’s difficult to identify those who have the drive to be scientists, or because it’s hard work to give them the support they need. Once we link them up to the right people it’s a pleasure to give them the support they need.

There have always been scientists who have come from impoverished or unlikely backgrounds, from Michael Faraday to Sophie Germaine, who fought hard to find their own way, often educating themselves. Who knows how many more advances we would have today if more of their contemporaries had access to a university education? In many cases the knowledge of children quickly outpaces that of their parents, and since parents can’t be expected to find the right resources the support must come from the schools. On the other hand there are many parents who desperately want their children to do well at school and encourage them to excel in as many subjects as possible (hence my initial skepticism when I first heard Calvin was “into science”.) This means that we also need to be wary of imposing our own biases on children. I can talk about particle physics with Calvin all day, but if he wants to study acoustic engineering then nobody should try to dissuade him from that. Nobody has a crystal ball that can tell them what path Calvin will choose to take, not even Calvin, so he needs the freedom to explore his interests in his own way.

Michael Faraday, a self-taught physicist from a poor background, giving a Royal Society Christmas Lecture, perhaps inspiring aspiring scientists in the audience. (Alexander Blaikley)

Michael Faraday, a self-taught physicist from a poor background, giving a Royal Society Christmas Lecture, perhaps inspiring aspiring scientists in the audience. (Alexander Blaikley)

So how can we encourage young scientists-in-the-making? It can be a daunting task, but from my own experience the key is to find the right people to help encourage the child. Finding someone who can share their joy and experiences of science is not easy, and it may mean second or third hand acquaintances. At the same time, there are many resources online you can use. Give a child a computer, a book of mathematical puzzles, and some very simple programming knowledge, and see them find their own solutions. Take them to museums, labs, and universities where they can meet real scientists who love to talk about their work. The key is to engage them and allow them to take part in the process. They can watch all the documentaries and read all the science books in the world, but that’s a passive exercise, and being a scientist is never passive. If a child wants to be an actor it’s not enough to ask them to read plays, they want to perform them. You’ll soon find out if your child is interested in science because they won’t be able to stop themselves being interested. The drive to solve problems and seek answers is not something that can be taught or taken away, but it can be encouraged or frustrated. Encouraging these interests is a long term investment, but one that is well worth the effort in every sense. Hopefully Calvin will be one of tomorrow’s scientists. He certainly has the ability, but more importantly he has the drive, and that means given the right support he’ll do great things.

“Girls aren’t good at science!”, Calvin said. So I told him that some of the best physicists I know are women. I explained how Marie Curie migrated from Poland to France about a century ago to study the new science of radioactivity, how she faced fierce sexism, and despite all that still became the first person in history to win two Nobel Prizes, for chemistry and physics. If a 10 year old thinks that only men can be good scientists then either the message isn’t getting through properly, or as science advocates we’re failing in our role to make it accessible to everyone. We need to move beyond the images of Einstein, Feynman, Cox, and Tyson in the public image of science.


The (seemingly) fractal nature of matter

Tuesday, May 27th, 2014

Matter and energy have a very curious property. They interact with each other in predictable ways and the more energy an object has, the smaller length scales it can interact with. This leads to some very interesting and beautiful results, which are best illustrated with some simple quantum electrodynamics (QED).

QED is the framework for describing the interactions of charged leptons with photons, and for now let’s limit things to electrons, positrons and photons. An electron is a negatively charged fundamental particle, and a positron is the same particle, but with a positive charge. A photon is a neutral fundamental particle of light and it interacts with anything that has a charge.

That means that we can draw a diagram of an interaction like the one below:

An electron radiating a photon

An electron radiating a photon

In this diagram, time flows from left to right, and the paths of the particles in space are represented in the up-down direction (and two additional directions if you have a good enough imagination to think in four dimensions!) The straight line with the arrow to the right is an electron, and the wavy line is a photon. In this diagram an electron emits a photon, which is a very simple process.

Let’s make something more complicated:

An electron and positron exchange a photon

An electron and positron make friends by exchanging a photon

In this diagram the line with the arrow to the left is a positron, and the electron and positron exchange a photon.

Things become more interesting when we join up the electron and positron lines like this:

An electron and positron annihilate

An electron and positron get a little too close and annihilate

Here an electron and positron annihilate to form a photon.

Now it turns out in quantum mechanics that we can’t just consider a single process, we have to consider all possible processes and sum up their contributions. So far only the second diagram we’ve considered actually reflects a real process, because the other two violate conservation of energy. So let’s look at electron-positron scattering. We have an electron and a positron in the initial state (the left hand side of the diagram) and in the final state (the right hand side of the diagram):

What happens in the middle?  According to quantum mechanics, everything possible!

What happens in the middle? According to quantum mechanics, everything possible!

There are two easy ways to join up the lines in this diagram to get the following contributions:

Two possible diagrams for electron-positron scattering

Two possible diagrams for electron-positron scattering

There’s a multiplicative weight (on the order of a percent) associated with each photon interaction, so we can count up the photons and determine the contribution each process has. In this case, there are two photon interactions in each diagram, so each one contributes roughly equally. (You may ask why we bother calculating the contributions for a given pair of initial and final states. In fact what we find interesting is the ratio of contributions for two different pairs of initial and final states so that we can make predictions about rates of interactions.)

Let’s add a photon to the diagram, just for fun. We can connect any two parts of electron and positron lines to create a photon, like so:

Taking up the complexity a notch, by adding a photon

Taking up the complexity a notch, by adding a photon

A fun game to play in you’re bored in a lecture is to see how many unique ways you can add a photon to a diagram.

So how do we turn this into a fractal? Well we start off with an electron moving through space (now omitting the particle labels for a cleaner diagram):

A lonely electron :(

A lonely electron 🙁

Then we add a photon or two to the diagram:

An electron with a photon

An electron with a photon

An electron hanging out with two photons

An electron hanging out with two photons

An electron going on an adventure with two photons

An electron going on an adventure with two photons

Similarly let’s start with a photon:

A boring photon being boring

A boring photon being boring

And add an electron-positron pair:

Ah, that's a bit more interesting

Ah, that’s a bit more interesting

This is all we need to get started. Every time we see an electron or positron line, we can replace it with a line that emits and absorbs a photon. Every time we see a photon we can add an electron-positron pair. We can keep repeating this process as much as we like until we end up with arbitrarily complex diagrams, each new step adding more refinement to the overall contributions:

A very busy electron

A very busy electron

At each step the distance we consider is smaller than the one before it, and the energy needed to probe this distance is larger. When we talk about an electron we usually think of a simple line, but real electrons are actually made of a mess of virtual particles that swarm around the central electron. The more energy we put into probing the electron’s structure (or lack of structure) the more particles we liberate in the process. There are many diagrams we can draw and we can’t pick out a single one of these diagrams as the “real” electron, as they all contribute. We have to take everything to get a real feel of what something as simple as an electron is.

As usual, things are even more complicated in reality than this simple picture. To get a complete understanding we should add the other particles to the diagrams. After all, that’s how we can get a Higgs boson out of proton- in some sense the Higgs boson was “already there” inside the proton and we just liberated it by adding a huge amount of energy. If things are tricky for the electron, they are even more complicated for the proton. Hadrons are bound states of quarks and gluons, and while we can see an individual electron, it’s impossible to see an individual quark. Quarks are always found in groups, so have the take the huge fractal into account when we look inside a proton and try to simulate what happens. This is an intractable problem, so need a lot of help from the experimental data to get it right, such as the dedicated deep inelastic scattering experiments at the DESY laboratory.

The view inside a proton might look a little like this (where the arrows represent quarks):

The crazy inner life of the proton

The crazy inner life of the proton

Except those extra bits would go on forever to the left and right, as indicated by the dotted lines, and instead of happening in one spatial dimension it happens in three. To make matters worse, the valence quarks are not just straight lines as I’ve drawn them here, they meander to and fro, changing their characteristic properties as they exchange other particles with each other.

Each time we reach a new energy range in our experiments, we get to prober deeper into this fractal structure of matter, and as we go to higher energies we also liberate higher mass particles. The fractals for quarks interact strongly, so they are dense and have high discovery potential. The fractals for neutrinos are very sparse and their interactions can spread over huge distances. Since all particles can interact with each other directly or through intermediaries, all these fractals interact with each other too. Each proton inside your body contains three valence quarks, surrounded by a fractal mess of quarks and gluons, exactly the same as those in the protons that fly around the LHC. All we’ve done at the LHC is probe further into those fractals to look for something new. At the same time, since the protons are indistinguishable they are very weakly connected to each other via quantum mechanics. In effect the fractals that surround every valence particle join up to make one cosmological fractal, and the valence particles just excitations of that fractal that managed to break free from their (anti-)matter counterparts.

The astute reader will remember that the title of the post was the seemingly fractal nature of matter. Everything that has been described so far fulfils the requirements of any fractal- self similarity, increased complexity with depth and so on. What it is that makes matter unlike a fractal? We don’t exactly know the answer to that question, but we do know that eventually the levels of complexity have to stop. We can’t keep splitting space up into smaller and smaller chunks and finding more and more complex arrangements of the same particles over and over again. This is because eventually we would reach the Planck scale, which is where the quantum effects of gravity become important and it becomes very difficult to keep track of spatial distances.

Meanwhile, deep inside an electron, something weird happens at the Planck scale

Meanwhile, deep inside an electron’s fractal, causality breaks down and something weird happens at the Planck scale

Nobody knows what lies at the Planck scale, although there are several interesting hypotheses. Perhaps the world is made of superstrings, and the particles we see are merely excitations of those strings. Some models propose a unification of all known forces into a single force. We know that the Planck scale is about fifteen orders of magnitude higher in energy than the LHC, so we’ll never reach the energy and length scales needed to answer these questions completely. However we’ve scratched the surface with the formulation of the Standard Model, and so far it’s been a frustratingly good model to work with. The interactions we know of are simple, elegant, and very subtle. The most precise tests of the Standard Model come from adding up just a handful of these fractal-like diagrams (at the cost of a huge amount of labour, calculations and experimental time.)

I find it mind boggling how such simple ideas can result in so much beauty, and yet it’s still somehow flawed. Whatever the reality is, it must be even more beautiful than what I described here, and we’ll probably never know its true nature.

(As a footnote, to please the pedants: To get a positron from an electron you also need to invert the coordinate axes to flip the spin. There are three distinct diagrams that contribute to the electron positron scattering, but the crossed diagram is a small detail might confuse someone new to these ideas.)


LHC Scientists face major setback

Tuesday, April 1st, 2014

1st April 2014. The LHC is currently in shutdown in preparation for the next physics run in 2015. However the record breaking accelerator is danger is falling far behind schedule as the engineers struggle with technical difficulties 100m below ground level.

The LHC tunnels house the 27km long particle accelerator in carefully controlled conditions. When the beams circulate they must be kept colder than anywhere else in the solar system, and with a vacuum more empty the voids of outer space. Any disruption to the cryogenic cooling systems or the vacuum systems can place serious strain on the operations timetable, and engineers have found signs of severe damage.

Scientists patrol the LHC, inspecting the damaged areas.

Scientists patrol the LHC, inspecting the damaged areas.

The first indications of problems were identified coming from Sector 7 between areas F and H. Cryogenics expert, Francis Urquhart said “My team noticed dents in the service pipes about 50cm from the floor. There was also a deposit of white fibrous foreign matter on some of the cable trays.” The pipes were replaced, but the damage returned the following day, and small black aromatic samples were found piled on the floor. These were sent for analysis and after chemical tests confirmed that they contained no liquid Helium, and that radiometry found they posed no ionisation risk, they were finally identified as Ovis aries depositions.

Ovis aries are found throughout the CERN site, so on-site contamination could not be ruled out. It is currently thought that the specimens entered the Super Proton Synchrotron (SPS) accelerator and proceeded from the SPS to the LHC, leaving deposits as they went. The expert in charge, Gabriella Oak, could not be reached for comment, but is said to be left feeling “rather sheepish”.

Elsewhere on the ring there was another breach of the security protocols as several specimens of Bovinae were found in the ring. The Bovinae are common in Switzerland and it due to their size, must have entered via one of the service elevators. All access points and elevators at the LHC are carefully controlled using biometry and retinal scans, making unauthorised entry virtually impossible. Upon being asked whether the Bovinae had been seen scanning their retinae at the security checkpoints, Francis Urquhart replied “You might very well think that. I could not possibly comment.” While evidence of such actions cannot be found CCTV footage, there have been signs of chewed cud found on the floor, and Bovinae deposits, which are significantly larger than the Ovis deposits, owing to the difference in size.

The retinal scans at the LHC are designed exclusively for human use. A search of the biometric record database show at least one individual (R Wiggum) with unusual retinae, affiliated to “Bovine University”.

It is not known exactly how much fauna is currently in the LHC tunnels, although it is thought to be at least 25 different specimens. They can be identified by the bells they carry around their necks, which can sound like klaxons when they charge. Until the fauna have been cleared, essential repair work is extremely difficult. “I was repairing some damage caused by a passing cow” said Stanford PhD student Cecilia, “when I thought I heard the low oxygen klaxon. By the time I realised it was just two sheep I had already put on my safety mask and pulled the alarm to evacuate the tunnels.” She then commented “It took us three hours to get access to the tunnels again, and the noises and lights had caused the animals to panic, creating even more damage to clean up.”

This is not the first time a complex of tunnels has been overrun by farm animals. In the early 90s the London Underground was found to be infested with horses, which turned into a longterm problem and took many years to resolve.

Current estimates on the delay to the schedule range from a few weeks to almost a decade. Head of ATLAS operations, Dr Remy Beauregard Hadley, comments “I can’t believe all this has happened. They talk about Bovinae deposits delaying the turn on, and I think it’s just a load of bullshit!”


Oh brave new world, which has such physicists in it!

Monday, February 10th, 2014

In August I moved away from CERN, and I’ve been back and forth between CERN and Brussels quite a lot since then. In fact right now I’m sitting in the building 40 where people go to drink coffee and have meetings, and I can see the ATLAS Higgs Convener sitting on the next table. All this leaves me feeling a little detached from what is really happening at CERN, as if it’s not “my” lab anymore, and that actually sums up how many people think about particle physics at the moment. With LHC Run I we found the Higgs boson. It was what most people expected to see, and by a large margin it was the most probable thing we would have discovered. Things will be different for Run II. Nobody has a good idea about what to expect in terms of new particles (and if they say they do have a good idea, they’re lying.) In that sense it’s not “our” dataset, it’s whatever nature decides it should be. All we can do is say what is possible, not what is probable. (Although we can probably say one scenario is more probable than another.)

The problem we now face is that there is no longer an obvious piece that’s missing, but there are still many unanswered questions, which means we have to move from an era of a well constrained search to an era of phenomenology, or looking for new effects in the data. That’s not a transition I’m entirely comfortable with for several reasons. It’s often said that nature is not spiteful, but it is subtle and indifferent to our expectations. There’s no reason to think that there “should” be new physics for us to discover as we increase the energy of the LHC, and we could be unlucky enough to not find anything new in the Run II dataset. A phenomenological search also means that we’d be overly sensitive to statistical bumps and dips in the data. Every time there’s a new peak that we don’t expect we have to exercise caution and skepticism, almost to the point where it stops being fun. Suppose we find an excess in a dijet spectrum. We may conclude that this is due a new particle, but if we’re going to be phenomenologists about it we must remain open minded, so we can’t necessarily expect to see the same particle in a dimuon final state. It would then be prudent to ask if such a peak comes from a poorly understood effect, such as jet energy scales, and those kinds of effects can be hard to untangle if we don’t have a good control sample in data. At least with the discovery of the Higgs boson, the top quark, and the W and Z bosons we knew what final states to expect and what ratios they should exhibit. There’s also something a little unsettling about not having a roadmap of what to expect. When asked to pick between several alternative scenarios that are neither favoured by evidence nor disfavoured by lack of evidence it’s hard to decide what to prioritise.

Take your pick of new physics!  Each scenario will have new phase space to explore in LHC Run II [CMS]

Take your pick of new physics! Each scenario will have new phase space to explore in LHC Run II [CMS]

On the other hand there is reason to be excited. Since we don’t know what to expect in LHC Run II, anything we do discover will change our views considerably, and will lead to a paradigm shift. If we do discover a new particle, or even better, a new sector of particles, it could help frame the Standard Model as a subset of something more elegant and unified. If that’s the case then we can look forward to decades of intense and exciting research, that would make the Higgs discovery look like small potatoes. So the next few years at the LHC could be either the most boring or the most exciting time in the history of particle physics, and we won’t know until we look at the data. Will nature tantalise us with hints of something novel, will it give us irrefutable evidence of a new resonance, or will it leave us with nothing new at all? For my part I’m taking on the dilepton final states. These are quick, clean, simple, and versatile signatures of something new that are not tied down to a specific model. That’s the best search I can perform in an environment of such uncertainty and with a lack of coherent direction. Let’s hope it pays off, and paves the way for even more discoveries.

What's happening at 325GeV at CDF?  Only more data can tell us! (CDF)

What’s happening at 325GeV at CDF? Only more data can tell us. Based on what the LHC has seen, this is probably a statistical fluctuation. (CDF)


Higgs Convert

Friday, November 29th, 2013

Since 4th July 2012, the physicists at CERN have had a new boson to play with. This new boson was first seen in the searches that were optimised to find the world famous Higgs boson, and the experiments went as far as to call it a “Higgs-like” boson. Since then there has been an intense program to study its spin, width, decay modes and couplings and so far it’s passed every test of Higgs-ness. Whether or not the new boson is the Standard Model Higgs boson is one of the most pressing questions facing us today, as there is still room for anomalous couplings. Whatever the answer is, a lot of physicists will be pleased. If we find that the properties match those of a Standard Model Higgs boson exactly then we will hail it as a triumph of science and a fitting end to the quest for the Standard Model which has taken the work of thousands of physicists over many decades. If we find some anomaly in the couplings this would be a hint to new physics hiding “just around the corner” and tease is with what we may see at higher energies when the LHC turns on again in 2015.

A candidate for a Higgs boson decaying to two tau leptons (ATLAS)

A candidate for a Higgs boson decaying to two tau leptons (ATLAS)

For those who have read my blog for a long time, you may remember that I wrote a post saying how I was skeptical that we would find the Standard Model Higgs boson. In fact I even bet a friend $20 that we wouldn’t find the Standard Model Higgs boson by 2020, and until today I’ve been holding on to my money. This week I found that ATLAS announced the results of their search for the Higgs boson decaying to two tau leptons, and the results agree with predictions. When we take this result alongside the decays to bosons, and the spin measurements it’s seems obvious that this is the Higgs boson that we were looking for. It’s not fermiophobic, and now we have direct evidence of this. We have see the ratio of the direct ferimonic couplings to direct bosonic couplings, and they agree very well. We’d had indirect evidence of fermionic couplings from the gluon fusion production, but it’s always reassuring to see the direct decays as well. (As a side note I’d like to point out that the study of the Higgs boson decaying to two tau leptons has been the result of a huge amount of very hard work. This is one of the most difficult channels to study, requiring a huge amount of knowledge and a wide variety of final states.)

Now the reason for my skepticism was not because I thought the Standard Model was wrong. In fact the Standard Model is annoyingly accurate in its predictions, making unexpected discoveries very difficult. What I objected to was the hyperbole that people were throwing around despite the sheer lack of evidence. If we’re going to be scientists we need to rely on the data to tell us what is real about the universe and not what some particular model says. If we consider an argument of naturalness (by which I mean how few new free terms we need to add to the existing edifice of data) then the Higgs boson is the best candidate for a new discovery. However that’s only an argument about plausibility and does not count as evidence in favour of the Higgs boson. Some people would say things like “We need a Higgs boson because we need a Brout-Englert-Higgs mechanism to break the electroweak symmetry.” It’s true that this symmetry needs to be broken, but if there’s no Higgs boson then this is not a problem with nature, it’s a problem with our models!

The fact that we’ve seen the Higgs boson actually makes me sad to a certain extent. The most natural and likely prediction has been fulfilled, and this has been a wonderful accomplishment, but it is possible that this will be the LHC’s only new discovery. As we move into LHC Run II will we see something new? Nobody knows, of course, but I would not be surprised if we just see more of the Standard Model. At least this time we’ll probably be more cautious about what we say in the absence of evidence. If someone says “Of course we’ll see strong evidence of supersymmetry in the LHC Run II dataset.” then I’ll bet them $20 we won’t, and this time I’ll probably collect some winnings!


Nobel Dreams

Friday, October 4th, 2013

The liveblog

Greeting from Brussels! This is my liveblog of the Nobel Prize Announcement Ceremony, bringing you the facts and the retweets as they happen.

14:14: Press Conference ongoing. “This is a great day for young people.”

13:56: A moving statement from Kibble (source):

I am glad to see that the Swedish Academy has recognized the importance of the mass-generating mechanism for gauge theories and the prediction of the Higgs boson, recently verified at CERN. My two collaborators, Gerald Guralnik and Carl Richard Hagen, and I contributed to that discovery, but our paper was unquestionably the last of the three to be published in Physical Review Letters in 1964 (though we naturally regard our treatment as the most thorough and complete) and it is therefore no surprise that the Swedish Academy felt unable to include us, constrained as they are by a self-imposed rule that the Prize cannot be shared by more than three people. My sincere congratulations go to the two Prize winners, François Englert and Peter Higgs. A sad omission from the list was Englert’s collaborator Robert Brout, now deceased.

13:37: CERN are holding a press conference at 14:00 (CET) link

13:22: Commentary continues at the Nobel Prize page. Currently discussing why the boson was so hard to find. “This particle has been looked for at every accelerator that has existed.”

13:20: As expected, so many news sites have been created: CMS, ATLAS, ULB, Edinburgh

13:14: I think my twitter account has exploded with tweets. Also, some Belgian news pages are down, probably due to high traffic. Wow!

13:11: Wow, what a great announcement. Too short though!

13:08: Find out more about the physics at Brussels, where the Brout-Englert-Higgs mechanism was born! The IIHE and the Nobel Prize

13:01: Englert is on the phone. Good to hear from him 🙂

12:59: Animation of the boson appearing, cool!

12:57: We just opened the champagne here at ULB!

12:52: Text for the announcement:

“For the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN’s Large Hadron Collider”

12:48: The award goes to Englert and Higgs!

12:44: One minute to go!

12:39: We all know what the Brout-Englert-Higgs mechanism is and what the boson discovery means, so let’s instead take a look at the other likely awards. The prize could go to the discovery of extra solar planets. 51 Pegasi b was an extra solar planet discovered in 1995, orbiting a sun-like star. This discovery could have far reaching implications. What would happen if we saw spectral lines suggesting the presence amino acids coming from the planet? (I’m not sure such a phenomenon is even possible, but if it is it would be a very strong indicator of RNA-like life from another planet.) That discovery took place 18 years ago, and the Brout-Englert-Higgs boson was discovered only one year ago. Either discovery would certainly be worthy of the prize.

12:33: A quantum approach to the delay problem:

Someone go observe the academy and make them leave this terrible superposition. (@lievenscheire)

12:32: Another possible reason for the delay:

There’ll be a new hunt for the #Higgs. He’s gone to the Highlands to avoid the fuss if he wins #nobelprize. Maybe reason for delay. (@BBCPallab)

12:31: The Nobel Prize committee are stalling by suggesting we look at previous awards. At least they are trying to keep up amused while we wait 🙂

12:29: Around the world people are patiently waiting. People from the US have been awake since 5:00am. In Marakech the ATLAS Collaboration looks on. Here are ULB/IIHE the cafeteria seem deserted. (I’m glad there’s a coffee machine on the desk next time mine.) I’m starting to think this is a plot to get some more media attention for what is bound to be a controversial year for physics. There are many good choices of topic this year, and even some of the topics have controversial choices of Laureates.

12:21: Some humourous speculation about the delay:

The Academy only has 3 #sigma evidence of more votes for than against, waiting for more data (@SethZenz)

They can’t get Comic Sans installed on the Academy’s computer (@orzelc)

The committee were mobbed trying to get across a cocktail party. (@AstroKatie)

12:07: The announcement is delayed until 12:45 CET. People are complaining about the background music!

11:58: The announcement is delayed until 12:30 CET.

11:44: According to the Guardian (source) there will be a delay of 30 minutes.

11:42: Just over two minutes to go. This could be a very exciting year for Belgium.

11:33: See the livecast.

Other info

On Tuesday October 8th the recipient(s) of the 2013 Nobel Prize in Physics will be announced. There has already been a lot of speculation about who might be the Nobel Laureates this year, and there is a lot of interest in the likely contenders! Each year Thomson Reuters publishes predictions of who might receive the Nobel Prizes, and this year they have narrowed the scope down to three likely awards in physics:

  • ‣ Francois Englert and Peter Higgs, for their prediction of the Brout-Englert-Higgs mechanism. (Brout is deceased and the Nobel Prize is not awarded posthumously.)
  • ‣ Hideo Hosono, for his discovery of iron-based superconductors.
  • ‣ Geoffrey Marcy, Michel Mayor, and Didier Queloz, for their discoveries of extrasolar planets.
The 2012 Nobel Prize Award Ceremony (Copyright © Nobel Media AB 2012 Photo: Alexander Mahmoud)

The 2012 Nobel Prize Award Ceremony (Copyright © Nobel Media AB 2012 Photo: Alexander Mahmoud)

There has also been speculation that either Anderson or Nambu may receive a second Nobel Prize for their work related to spontaneous symmetry breaking.

With so many different predictions and so many opinions it can be hard to keep up with all the latest news and blogs! I know that a lot of people plan to share their views and experiences of the day, so I’ll be keep a list of bloggers and tweeters that you can follow.

Seth Zenz:

See Seth’s excellent post about the Nobel Prize, Englert and Higgs, and CERN. You can also follow his twitter account: @SethZenz

James Doherty:

See James’s great post about the Nobel Prize, He’s on twitter too: @JimmyDocco

Guardian liveblog

Other twitter accounts to follow:






Gauge transformation

Tuesday, October 1st, 2013

“Welcome to CMS,” my friend said, “it’s exactly the same as ATLAS, except the fluctuations are downward.” It was a light hearted, almost flippant remark and to an extent it summarised my feelings about the two experiments. So when I moved from the ATLAS experiment to the CMS experiment the biggest changes were not related to the physics. After all, we see the same physics, publish very similar results and analyse the same beams colliding over and over again. The big news that both experiments celebrate the most is, of course, the new boson. ATLAS saw a little more events than they expected in the main channels, and CMS saw a little fewer, and otherwise they both saw the same effect, confirming that it was real.

Aidan at ATLAS

Aidan at CMS

Same experience, different detectors. Nothing really changes!

What really changes is everything surrounding the work. I’ve moved across the world a few times to follow my career, first to California where we analysed collisions at SLAC, and then to CERN to work on ATLAS. This time I moved to ULB in Brussels, the capital of Europe, and that meant a new home, a new nation, a new university, and a new experiment. In fact the only thing that stayed the same were the protons. For me that’s perfect, after all the last thing I want to do is stagnate, doing the same thing day after day. A change like this is refreshing, gives a chance to open up new horizons and reinvent oneself a little. Having those tiny little protons be the only source of continuity is actually quite reassuring in a way. That’s what I’m here for, after all. To keep studying those protons I’ll let everything else around me change and welcome the state of flux.

So as well as all those “auxiliary” changes I decided to change the physics topic as well. I have previously searched for the Higgs boson, starting up and leading a new analysis from scratch before handing it over to the ATLAS machine. This time I’m looking for the Z prime boson, which has a clean signature and if it is seen, it is seen very soon after taking new data. There are several models out there, but given the relative ease and speed of discovery it’s more a matter of “Find now, ask questions later!” Within the first few weeks of taking data we will be poring over the results, looking for any hints of new physics, competing in a head to head race with ATLAS and with each other to find the peak first. If if exists, we’ll find it, and it’ll shake our view of physics at the TeV scale. This is a very different kind of physics for me, and at first it was not I felt particularly comfortable pursuing. I was used to having an airtight model that told me what to expect and how much of it to expect and even where to expect it. This time the data is telling the story and that’s a tricky idea to get used to. Then again this whole transition is about changing my outlook, so why not change analysis style too?

Grand Place

Finding the best table in Brussels and having dinner with a visiting friend.

For those who noticed my absence, I’m sorry! It’s taken a few months from the start of a job search in a very difficult job market, applying to positions on three different experiments, in four different countries. The move from one place to another is never particularly “clean” either, as there are loose ends from my old job, and it takes a while to get started in my new position. Then there are all those small changes, like a different ID card, a different currency, a slightly different style of French. I’ve let it take longer than I should have before returning to blogging because to be honest the break has been a very welcome one. CERN is a very busy place with long days and huge demands. Moving to Brussels was hard work at first, but now I find myself with more space, more time and more opportunities to catch up with everything in my life that was put on the back-burner. A decade of photos to sort, all those books I bought and put on the shelf, the half-finished ideas that got archived for when I got around to it. Contributing to this blog again is part of the grand plan. There are so many topics I want to touch on, and I set a very high bar with the Advent Calendar last year! I also want to look beyond science to the pursuit of knowledge itself and its implications on theology (something I never felt comfortable tackling when working for a US institute.)

The way I see it, moving experiment is just like a gauge transformation. No matter what happens, any physical phenomenon must be the same after a gauge transformation. This kind of transformation is a subtle mathematical change that has no classical analog. By making a phenomenon gauge invariant we can introduce new forces that mop up all the differences, so that ultimately, we all see the same thing, no matter how we look at it. In this case, what stays the same is the underlying nature of those colliding protons. That’s the gauge invariance, and everything else, the movement from place to place, from one experiment to another, are just the fields swooshing about as we perform our own personal gauge transformations. It turns out life is complex.