I went to the Chocolate Festival in Versoix, Switzerland on Saturday. As a tie-in with the International Year of Astronomy (by the way, here is the cosmicdiary blog), 13 chocolatiers made astronomy-related chocolate creations. You can see a few of them above (click twice for big versions) including my favorite, the bunny. Yes, that is a chocolate bunny astronaut planting a carrot flag.

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Early on in my student career, I learned that a favorite excuse of physicists is that we are beholden to take “whatever works” in the task of describing Nature. Sure, sure, we do give some degree of greater weight to “beautiful” theories (some of us moreso than others), but on the whole we are a culture of pragmatists. We tease our mathematician compatriots rather a lot for lack of proper respect for a correspondence of theory to reality. And in front of an experimental physicist audience, it really is best not to talk too loudly about things that cannot be proven one way or the other by observation.

But don’t let the simplicity of “whatever works” fool you. I can’t imagine that any good physicist would actually be happy to accept and/or use a method that just so happens to predict reality, without some kind of deeper understanding of why it works, how far it can be pushed, and where it can break down. In fact I would dare to say that in the majority of experimental physics analyses, only a small fraction of the effort goes into performing the measurement itself, and the rest is spent chasing down and quantifying all the uncertainties one has to acknowledge about various aspects of the method.

What I find quite amazing is that every generation of physicist manages to be trained in the scientific method almost entirely by example. In Math one is taught the rules of deduction, and there is little ambiguity in what constitutes a valid mathematical proof starting from the axioms and down every link in the chain onwards to the hypothesis. There is no such uniformity in Physics; in fact, there may not even be any requirement that a physics graduate have any knowledge of formal logic. Now, I don’t mean to say that the Quod Erat Demonstrandum structure of Math is or should be equally applicable to Science. While one can use “A→B” in Math to show that B is true (after having shown that A is true), the same statement in Science is only good to whatever uncertainty — and, more importantly, whatever other “hidden” variables went into controlling the behavior of A, B, and A→B. If scientists tried to achieve as much formal rigor in their reasoning as mathematicians do, I’m not sure we would be able to make appreciable progress. And this is where another “whatever works” often comes in — even if unable to fully list and/or address all the issues in the scientific chain, one can hope to do something reasonable, and then check the answer against some kind of control region (a.k.a. lab test) in order to argue that it should work in the region of interest.

If you think that the above paragraph is cryptic and rambling, imagine trying to convey the hows of this thinking process to a student fresh out of classes, where all theories and experimental results have been neatly laid out, and even with exactly the required pieces of information, no more, no less. The actual process of research is nothing so linear or finite. A good researcher has to keep an eye on almost everything, because it is anybody’s guess as to what is necessary, important, or prone to breaking. And just because “whatever works” happens to work, does not mean that one  has demonstrated that it is not a lucky accident. And unfortunately, it seems like the burden of scientific proof is one of the most difficult things to learn in this apprenticeship.

[ On the very incomprehensible drawing : The grey blocks are a histogram. The red things are for you to interprete. The background is supposed to be waves, but apparently those are way outside of my technical ability. ]

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One of my favorite things about moving to CERN two years ago was being able to work inside the ATLAS detector while it was still being constructed. The first time I went down to see the detector in 2006, I was on an official tour and could only walk around the outside of it. When I returned as a postdoc in 2007, I got to wear a real helmet with a headlamp and climb ladders into the detector itself. I don’t think I stopped smiling the whole day. It was hot down there in the summer, and loud, and sometimes dim in the place where you wished there was more light (hence the headlamp), but I had a lot of fun being there.

When I recently discovered Peter McCready’s website with images of the ATLAS cavern, the thing that impressed me most was the sound associated with the images. It’s not much, but the background noise of clanking and hammering really took me back to the days I spent there. On his site, you, too, can visit the ATLAS cavern and hear the sounds of the work being done. Use your mouse to look around, as though you are turning your head left, right, up or down.  You can also look down the length of the Large Hadron Collider tunnel.  In one image of the CMS detector, you can see the pipe that the LHC beam will go through, as though it is above your head!  You can also click to the next image using the black arrows to the left and right to see more of CMS, ATLAS, and the LHC.

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As has been mentioned in various earlier posts, there is a lot of excitement about the stimulus package (aka the American Recovery and Reinvestment Act) passed into law last month, and the new funds that are being made available for scientific research as a result.  It’s a substantial sum of money, in the billions of dollars — you can read a description here of what funds have been distributed where for science.  By my reading, the Department of Energy Office of Science is getting an additional $1.6B, and the National Science Foundation is getting $2.5B into its “research and related activities” account.  (These two agencies provide the great bulk of support for particle physics research in the US.)  Now the big question: how exactly will that money be distributed?

Every agency is going to have its own rules and its own set of priorities, and they need to be in line with the stimulus bill’s strict requirements on tracking how the funds are spent.  But we now have one set of clues, in the form of a memo from Arden Bement, the director of the NSF.  Their approach is to not create new programs that solicit new proposals, but to fund as many of the already-submitted proposals that have gotten excellent ratings from peer reviewers but have gone un-funded due to lack of resources.  One explicit goal that is stated is to fund excellent proposals submitted by researchers who have never held an NSF grant before — the young (or at least younger) people who will be the backbone of science over the next ten or twenty years.

I personally think that this is a very good approach.  There is currently a surplus of good ideas in science — there is so much more that we could do if we only had the resources.  Consider some of the statistics:  In 2007, only 26 percent of proposals to NSF were funded, down from 33 percent in 2000.  (It’s a little better in Mathematics and Physical Sciences, where 32 percent of proposals were funded in 2007.)  If you have never won an NSF grant before, you have only a 19% chance of getting your proposal funded, compared to 30% if you have won before.  About 25% of proposals that are rated excellent by reviewers aren’t funded, while more than 50% of those rated very good to excellent are rejected.  In 2007, that was a total of 6,297 proposals the NSF and the peer reviewers would wanted to have funded if there were sufficient resources available.

Rejected proposals that were rated as stronger than the average accepted proposal requested a total of $1.8B.  ”Over the last ten years, NSF’s capacity to fund these highly rated proposals has diminished.  In FY 1997, the ratio of awards to highly rated declines was 5:1; in FY 2007, that ratio had dropped to less than 2:1. NSF is thus supporting a smaller proportion of potentially fundable proposals.  These declined proposals represent a rich portfolio of unfunded opportunities, proposals that if funded may have produced substantial research and education benefits.”

$2.5B will go a long way towards clearing this backlog.  Our shovels are ready.

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On March 9, Barack Obama signed the Presidential Memorandum on Scientific Integrity.

The memo basically says:

• Candidates for science positions should be selected based on the candidate’s knowledge, credentials, experience, and integrity
• Scientific information considered in policy decisions should be subject to peer review
• Scientific findings should be made available to the public

You probably won’t be surprised that as a scientist I think this is fantastic. Hopefully, this change in attitude towards science by the federal government helps improve the attitude towards science in our society overall. I think that we can only solve many of today’s problems by relying on a scientific approach.
This statement, along with the recently passed stimulus and budget bills seem to indicate the start of a period where we are investing heavily again in basic research. Time and time again, this has been shown to be a great use of resources.

The sculpture in the photo is just outside my office. The Nataraja is trampling a dwarf that represents ignorance. Scientific research is an organized fight against our ignorance of the universe. Let’s make trampling ignorance our goal.

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I would never claim that I work harder than average for people on my experiment, but I do think I work stranger hours.  I’m likely to check my email first thing in the morning, rather than waiting to get to work, or before I go to bed when I come home exhausted from a Friday night party.  And, if there’s something quick that needs to be done, I generally do it immediately.

What could persuade me to do work at such odd hours?  Well,  remember, ATLAS is a world-spanning collaboration.  My collaborators may be working at any time, whether it’s day or night for me, and we have computers doing testing, simulation, and analysis for us continuously.  A colleague of mine might need help before he can continue his work; one of the professors I’m working with back in Berkeley might have some time to investigate a problem I found, if only I’ll give her more information about it; the disk that stores the results for a software testing suite might be about to fill up.  If I update myself at the right time and take action, my colleagues can get their work done (or help me), the software tests can proceed without problems, and so on.

I would almost never miss a dinner with friends, a hike, or a weekend trip to do work.  But between those things, a quick email check and a little effort on my part can make a larger difference in the work done by the collaboration as a whole.  Nothing I can do will make a big difference for the experiment, but when others do the same, it adds up.

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The  CMS collaboration is made up of about 3600 people coming from 183 institutes in 38 countries. Besides the United States, there are large representations from Western Europe, Eastern Europe, Russia, Asia and… well just about everywhere. In fact, it is probably easier to list the areas where we don’t have collaborators: notably Africa, Canada (the Canadians seem to prefer ATLAS) and Australia (also ATLAS).  As a result, my collaborators come from diverse cultures, religions and mother languages and the only thing we have in common is an unstoppable curiosity of how the universe works. We do have culture clashes, but we try to rise above them. I remember during a particularly conflictual meeting being chaired at CERN (pre CMS days) by a German colleague, one of our French colleagues got so angry he said “We threw you out of France before and we can do it again!” The room got very quiet as most participants looked uncomfortably at their shoes. These kind of direct cultural references are rare, though, and mostly you think of your colleagues as your fellow researcher and not as Russian, Turkish, Chinese or Georgian.

Many countries or set of countries have so many collaborators that they form their own mini-collaboration structure so that they can better deploy their own people in the larger context of CMS. For example, the US has a mini-collaboration: USCMS which comprises all the US institutions working on CMS. Last fall I was invited to the CMS RDMS collaboration meeting to give an overview of the particular physics I am interested in. RDMS stands for Russia-Dubna Member States, and is made up of the CMS collaborating institutions in Russia, Armenia, Belarus, Bulgaria, Czech Republic, Georgia, Slovak Republic, Ukraine and Uzbekistan. This past year, the RDMS collaboration meeting was held in Minsk, Belarus. Belarus is a tiny country between Poland and Russia and was part of the Soviet Union until 1991 when it declared its independence. It has its own language, Belarusian, although most people there also speak Russian. Not that that helped me at all — I don’t speak Russian or Belarusian.

The RDMS collaboration is very active in CMS and during this collaboration meeting I got to learn more about what they were doing as well as summarizing work in my particular area. Our hosts in Minsk were terrific and in addition to scientific meetings they gave us a tour of Minsk, took us to the opera, to the symphony and to museums. Our meeting was even featured on the national news along with film footage of the foreign scientists. I returned to CERN feeling much better connected with my RDMS colleagues and with plans to strengthen ties with them in my particular data analysis interests.

Months after the meeting ended, I received an email from the Chicago Field Office (I work for Fermilab, just outside of Chicago, Illinois), Office of Intelligence and Counterintelligence asking for details on my trip to Belarus. They were particularly interested in any connections I had made, especially on a personal level, with people I met at the conference. They also wanted to know if there was any chance my laptop computer had been tampered with or if my room had been searched or if people seemed to know more about me than would be normal. Not only did they want to know what hotel I stayed in, but also they wanted the room and floor number. I should mention that I can’t even remember what I ate yesterday; I certainly can’t remember the room number of the hotel I stayed in six months ago. Of course I understand why we worry about these things, and I am not naive enough to believe that there was no possibility that I was spied on (although I don’t think I know anything particularly interesting), but it does make me realize that the world I live and work in is very special place, where country boundaries are often not noticed, at least not by my fellow researchers.

Subsequently, I had the possibility to lecture at a summer school in Iran, the First IPM Meeting on LHC Physics. Unfortunately this trip didn’t even get off the ground: judging by the collective guffaw from everyone I mentioned it to, I decided to save myself the pain of filling in forms in triplicate just to amuse the State Department and/or the Department of Energy for the two seconds it would take them to say no.

One of the great things about this field, and about international scientific collaboration is the opportunity to work and visit scientists from around the world. In general we speak the same language (physics) and we work hard at not forcing our own culture, religion, politics or ideology on others. Our biggest arguments are about how to optimize our detector and how to define which data to collect and how to interpret it. Luckily there is plenty of material there to argue about without resorting to politics or religion.

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Happy 20th anniversary (or Bonne Anniversaire), “uniform resource locator” and “hyper text transfer protocol”!

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I was wandering through some of the media results of last fall (procrastinating on writing more lecture notes) and came across the Scientific American podcast with both Frank Wilczek and editor George Musser talking about the LHC and all manner of particle physics stuff.  At some point the interviewer asked George whether the “Large” in “Large Hadron Collider” described the hadrons or the collider.  George of course said it’s the collider, the hadrons are all about the same size, “ten to the minus fifteen meters”.  However, the transcription says:

Musser: … and the energies they have, but they are all 10 to 15 meters across, the protons.

A proton the size of a bus!  Now there’s a Nobel winning find for you.

This just shows the pratfalls of all the media interest – it is a tricky business to convey the message in terms people can grok.  Here a simple slip-up in transcribing scientific notation leads to an error of a factor of 10 quintillion (10,000,000,000,000,000)- (although I’d expect Scientific American to do a little better).  It’s a little like playing the “telephone game” – you whisper something sensible to someone, they whisper it to the next person, who whispers to the next, and 10 people down the line the message is some odd permutation of the original.

Anyway, I got a kick out of the idea of a gargantuan proton.  I hope no lawsuits ensue.

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Update 13 March: The Tevatron experiments have just released new, stronger limits on the mass of the Higgs boson.  Read about it here.

There have been a couple new results from the Tevatron this week.

The first result, shown by both CDF and DØ experiments, is the observation of single top production. The top quark was first observed in 1995 by the same two experiments, but that observation was of top pair production (a top plus its antiparticle). This discovery was of single top quarks, with no antiparticle partner.  In the Standard Model of particle physics, top pair production occurs roughly twice as often as single top production, and the top pair signal is also somewhat easier to see in data. The observation of single top production is important, because even though everyone expected the process to exist, demonstrating sensitivity to such a rare and difficult signal is an important milestone on the way to searches for even rarer processes, like production of a Higgs boson.

The other result is the most precise measurement (by a single experiment) to date of the W boson mass, by DØ. Whereas the single top measurement demonstrates increasing sensitivity to the Higgs, the W mass tells us what mass of Higgs boson we might expect. Since the mass of the W is supposed to come from the Higgs mechanism, a more precise measurement narrows the window of likely Higgs masses. The mass of the Higgs has interesting implications for current searches at the Tevatron and the upcoming searches at the LHC, because the Higgs may be more difficult to see depending on its mass.

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The film crew for Particle Fever was in my office again last week.  It’s a movie in which I, if I’m not cut, will play the role of Seth Zenz, a graduate student with a high opinion of himself who wants to be on TV.  The filming this time was a rather fun and slightly surreal experience: the director has a bunch of us sit down and, well, act like ourselves.  We get to have real conversations about things we’re working on, but there are a few things we have to do differently.  We can’t take quite so much vocabulary and background knowledge for granted, in the hope that maybe the audience can understand us.  We also have to try not to interrupt each other, which is a very big change indeed from how we usually have discussions!  And we have to sit on tables and in other funny places so we all fit in a good camera shot.   It probably really is the closest anyone get to reproducing a bit of our lives and thought processes for the public, but everything sure does feel different in front of a camera.

Note to self: make sure to replace the last part of the second sentence with “an earnest desire to explain the importance and excitement of his work to the public” before posting this!

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Science writer John Tierney held a Darwin Birthday Song Contest and just announced the winners, one a non-Darwin tribute to Einstein called “I’m a Genius” by a Broadway song writer and Einstein look-a-like  Ray Jessel, and the Darwin-based “Mr. Darwin, Mr. Wallace, Mr. Matthew” by British songwriter David Haines.   (I was very intrigued to hear that the contest was judged by Richard Milner, singing scientist, thinking I had discovered a completely unexpected alternative career of my colleague at MIT, but it isn’t that Richard Milner, it’s another one…)  Thinking about how katAlp’s rap raced around the world last year, I propose the same-write a song about the LHC or particle physics in general, put it in a comment here, (or better yet, record it and drop in a link) and we’ll have a doodle poll to pick the winner.  I’m hoping we do better than my last attempt at musical adventure.  I have yet to conceive of a prize, so suggestions along those lines are welcome as well, but remember, we do physics for the love of knowledge, not for the money.

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There is a lot of buzz about the world’s largest ‘atom smasher’, the LHC, and rightfully so. And if you peel away the glamour of the machine itself, there is some of the most exciting science still to discover. We have predictions paving the way to new frontiers, such as the Higgs, supersymmetry, Dark Energy, extra dimensions, and the list goes on and on.

But after some weeks of reading article after article I can’t stop wondering: what ever happened to good old fashioned Quantum Chromo Dynamics ? Have we unraveled the mysteries of asymptotic freedom, of deconfinement and chiral symmetry restoration, and I just missed it ? Have we experimentally verified a nobel prize winning theory that still left much to be understood ? Have we indeed cracked the fundamental question of matter formation in the universe ? I would venture to say ‘no’ to most of these questions.

And you might say, wait a minute, doesn’t electro-weak symmetry breaking and the potential discovery of the Higgs solve all our remaining questions about matter and mass. Well, does it ? I am talking about the good old proton or neutron here. The building blocks of nature. How do these hadrons come about, how does hadronization occur, this extreme jump in mass, this unique principle of confinement ? Somehow high energy physics has largely turned away from this fundamental process in QCD. Too complicated, not calculable, not first principle, not fundamental (?) etc. etc. And there are at least some factorizable theories, such as fragmentation, or some neat lattice QCD calculations, to answer most of it. Yup, tell that to your first year graduate student. Well, there once was a quark, very energetic and then suddenly it decided to break up into many hadrons just like that. Pleeease. This is where the phrase ‘…and then a miracle occurred..’ enters into our fundamental understanding of nature.

And people will argue with me that much more is understood and on good footing, and they are probably right, but a.) we have stopped investing a lot into the experimental verification of the phenomenon of hadronization and b.) as long as constituent quarks, instantons, sphalerons and even more exotic states are allowed as explanations for the most basic process in the evolution in our universe I don’t feel that the book is closed and that we have achieved a really deep understanding.

Admittedly there are QCD physics groups in all the three major experiments at the LHC, but the buzz seems to focus more on exotica and smartly labeled ‘new physics’ rather than on the questions that should interest all of us the most. 

And let’s not forget that there were some recent experimental breakthroughs on QCD physics. Mostly from RHIC, which now has unambiguously proven that a deconfined state of matter exists at a sufficiently high temperature. It behaves weird though, more like a perfect liquid with strongly coupled degrees of freedom, rather than a weakly coupled plasma.  But it is deconfined, so it unravels one of the QCD pillars experimentally. Its preferred re-confinement method seems to be recombination of quarks, though, rather than fragmentation, which is in blatant disagreement with one of the oldest accepted models in elementary particle physics. So maybe the hadronization in medium is different than the hadronization in vacuum ? And if so, which one is relevant for the generation of matter in the evolution of the universe ? Was the universe a vacuum or a deconfined medium at the time of hadronization ?

And in addition there is still very little evidence for the other pillar of QCD, chiral symmetry restoration, which tries to convince us that a massive universe will turn into a state than can be described by a massless symmetry theory (QCD) above a certain temperature. Pretty dramatic, hmmm ? And still not experimentally verified.

So let’s turn part of our attention back to the basics. It’s true that verification of the chiral transition will likely require heavy ions and is thus the strong suit of ALICE, but also the more limited heavy ion programs in CMS and ATLAS as well as the proton-proton programs in all three experiments can make fundamental measurements to the question of generation of QCD mass, not Higgs mass, in nature. And to me that is more interesting than all the exotica that might or might not prove Gene Rodenberry and Isaac Asimov right. Just call me old fashioned.

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“Travel the world, visit exotic places, see the same hundred people at each of them” is how one of my colleagues describes his life in particle physics.  There is some truth to it — given that I and my collaborators are distributed all over the world, we might as well meet up at places other than CERN now and then, and why not go somewhere interesting?

This week I went to the annual “all hands” meeting of the Open Science Grid.  The OSG provides the underlying grid middleware that supports LHC computing in the United States, and many other scientific collaborations that do large-scale, highly-distributed computing.  One of those collaborations is the Laser Interferometry Gravitation Observatory (LIGO), so this year the meeting was held at one of LIGO’s experimental sites in Livingston, LA (about a half hour’s drive east of Baton Rouge).

It’s always fun to go see someone else’s physics experiment!  With apologies to the people who work on LIGO, here’s how I understand it to work, in just one paragraph.  Einstein’s theory of gravity predicts that astronomical systems such as binary stars can emit gravitational waves, which are propagating variations in the fabric of space-time. As they pass through some region of space, they will cause the distance between two points in space to change.  So, LIGO measures the distance between sets of mirrors that are separated by 4 km in the hope of seeing that distance vary (and better still, correlating that event with some event that can be observed in the sky).  But these effects will be very small, such that the mirrors will only be displaced by a small fraction of the radius of the proton.  That means that you have to isolate the mirrors from the rest of the environment as well as possible, and then understand all sorts of environmental effects so that you can account for them in your measurements of the distances.  This is an extremely difficult experiment, and with the current version of LIGO, the experimenters only expect to see one gravitational wave event every ten years.  They are currently implementing upgrades that will increase their sensitivity to the point where they can observe tens of events (or more) every year.  If they can make it work, it will provide a new way to look at the sky that can bring complementary information, just as every wavelength of light used in astronomy tells us something new.  (OK, it was a long paragraph.)

So we all got to see the two long perpendicular tunnels on the site, although we weren’t able to go inside to see the apparaturs itself.  We also got to hear about the particular computing challenges that LIGO faces.  They produce about a terabyte of data each day, which is a factor of several less than what we would expect out of CMS.  Only about 1% of that data is needed to make the distance measurements; the rest is all the information about the environment.  What is most important for LIGO is turnaround — they want to be able to analyze the data in as close to real time as possible, so that if they observe something interesting, they can alert other astronomers who can try to make confirming observations. 

Of course, this visit wasn’t all fun and games (or crawfish, which is none of the above) for me.  We also had the annual get-together of the staff of the seven US CMS Tier-2 computing sites.  We do a videoconference every two weeks to keep ourselves informed of what is going on, but it is nice to actually get everyone in the same room once a year; all those conversations that usually happen through email (see my previous complaints) or instant messaging (perhaps even worse!) can happen face to face.  This year we spent a lot of time talking about what we can do to improve the reliability of site operations (if anything), our high-level plans for the next year, and what systems we may want to use to manage our disk storage in the future.  This last item got a lot of attention; we chose our current system more than four years ago, and people had a lot of enthusiasm for some alternatives that have emerged since then.  We’ll see how that turns out!

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“I’d join you, but I think I’m close to locating a gluino, which would completely validate Supersymmetrical Theory if we could include it in the bestiary.”

– Doctor Manhattan, from Alan Moore and Dave Gibbons’ Watchmen

My friends and I watch Watchmen tonight.  I read the comic book not long ago and loved it.  While I have my doubts that the movie can live up to the original, I have to see it just in case — and anyway, it will be fun.

Doctor Manhattan, the character quoted above, is an obvious hero to people in my profession.  A physicist by training and demigod by accident, he is somewhat socially ill-adjusted but does unparalleled work in understanding the subatomic makeup of the universe.  He can also explode things with the power of his mind, which we can’t do, but which would be useful from time to time in traffic.

This promises to be the most entertaining CERN group movie-watching since the particle accelererator scene in Terminator 3.

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