A dubious offer April 30, 2007
Posted by dorigo in internet, italian blogs, personal, politics.2 comments
As I had a chance to mention in a post, a few weeks ago I received an offer from a major italian newspaper , to write a blog for them.
The newspaper, Il Sole-24 Ore , had contacted me earlier in March to inquire about the “New Scientist/Economist affair” - the appearance on those magazines of imprecise information on the possible Higgs boson signal seen by CDF, something of which John Conway over at Cosmic Variance and myself here had been blamed as partly responsible (we were not, although I did apologize later to my colleagues in CDF, since some had felt betrayed by our blogging activities). At the time, I had had the pleasure of talking with serious journalists from Il Sole, which had then used in a correct way the information I had provided. A relatively error-free account of the matter had appeared in the Thursday cultural insert of the newspaper, and I had had a good impression of their professionalism.
The offer I received shortly thereafter from the same publisher consisted in becoming a blogger in the context of a new project that was to start in May on the web site “NOVA”, together with as many as 100 other “innovauthors”, as they called us - more or less known personalities of the cultural scene in Italy. Among the 100 there were going to be illustrious scientists like Margherita Hack , well-known writers such as Daniele del Giudice, successful filmmakers as Gabriele Salvatores , exhilarating cartoonists like Stefano Disegni , and other figures like Lapo Elkann, to which I would prefer not to attach any adjectives here (he is quite wealthy and I would be quite sued). All in all, a pretty weird group of people, but my admiration for Hack in particular had kept my interest going at the start.
The idea was that we would have a blog within their web site, where we could write anything we liked, provided we kept it original, innovative, and interesting. No problem with that. However, our pages would run advertisements of which we had no control - a fact that really bothered me for the daily potential of making me mad (I could in fact imagine quite a few ads that would make me sick - and I would be working to sell the product regardless).
A second problem I soon envisioned, as the picture became less sketchy, was the fact that we would have no control on the visual appearance of our pages. And we would not be provided with any form of statistics of visitors, incoming links, nothing. The latter thing is quite unacceptable, as any mature blogger would agree: understanding what is read and what is not, from whom, and what gets linked, is of vital importance for a serious blogging activity.
And then I received by e-mail the contract they offered. I was really surprised: I would be paid 0.10 euro per every monthly visitor (meaning 10 cents for a visitor who came once a month just as much as 10 cents for a visitor who came 100 times during the same month), but I would have no means of controlling the incoming traffic!
Now, while the hypothetical remuneration did not look too bad - a high-traffic site might easily provide its bloggers with several thousand monthly visitors, without any special effort on their part - the conditions of the contract looked ridiculous: by being prevented from verifying the traffic, the blogger would be left in the dark on whether the publisher was paying or not the right amount. A contract, I reasoned, had to be something which made any money exchange transparent to both parties. I felt I was asked to sign something that only protected my publisher.
Other conditions in the contract also upset me. I was conceding to my publisher the copyright of whatever I wrote; I was assuming total liability both towards my publisher and towards third parties, and I was also going to be liable for what commenters wrote on my posts; I was not to write anything that could damage the image of Sole-24 Ore, either. And so on. Basically, I was going to be on a leash, for a dubious income, and I was selling the rights of what I would write.
Despite this setback, I really wanted to accept the offer. I was curious to see what would happen, and I had a large amount of material to write about: I reasoned that, worse coming to worst, just translating the most interesting posts I had written in English during the last two years would have kept me going for a few months, so the extra workload did not look too threatening (something to take in account because, of course, I was not going to stop writing my private blog here anyhow).
I decided to negotiate better conditions. In particular, I wanted to be guaranteed I would have a means of controlling the traffic to my site.
(To be continued…)
The say of the week - and commentary April 30, 2007
Posted by dorigo in humor, personal, physics, science.14 comments
“You do not really understand something unless you can explain it to your grandmother.”(Albert Einstein)
Which really means I am not going to understand anything more, since both my grandmothers have passed away…. That might also explain why they say that if you are going to make a significant contribution to the field of Physics, you’ll do so at a fairly young age.
I do like the game of taking a solemn sentence and turning its meaning upside down. You learn something from it at times. Take the following: “If I have seen further it is by standing on the shoulders of giants“, by Isaac Newton. One could modify it as follows: “If I have not seen further, it is by standing in the footprints of giants“. Which makes sense, since once the giant is gone he or she leaves a furrow which is difficult to jump out of…
Lost music April 29, 2007
Posted by dorigo in Art, music, news.4 comments
We all lose when an artist of the caliber of Mstislav Rostropovich passes away. He was 80, and played the Cello like nobody. The Cello is a wonderful instrument, one that very few artists get to master to perfection. But Rostropovich was not only a Cello player: he was a composer and a director of Orchestra. And an opposer of the regime, who fled Russia in 1974.
Explaining the naturalness problem April 27, 2007
Posted by dorigo in internet, news, physics, science.23 comments
I just read the insightful slides presented by Michelangelo Mangano at IFAE 2007 last month, in his plenary talk titled “Stato e prospettive della Fisica delle Particelle” (Status and prospects of Particle Physics). His slides are in English, and you are well advised to have a look at them.
Michelangelo points out from the outset what are the possible outcomes of the searches for the Higgs boson at the LHC. He foresees a situation when:
- the SM Higgs is found, it is light, and everything goes well. In that case, a pressing question to answer will be the one of the naturalness (see below).
- the SM Higgs is not found below 0.8-1 TeV of mass. If that happens, it may be because of either:
- cross section below SM predictions, and that is New Physics;
- Visible branching ratios below SM values, and that is also New Physics;
- H exists but has a mass above 800 GeV, and that, too, means New Physics.
Talking about the naturalness problem, Michelangelo puts things in a way even me and you can understand. He basically says: radiative corrections to the Higgs mass amount to a sum of different terms whose value gets multiplied by the square of the energy at which the Standard Model breaks down. If that energy scale is as large as the Planck mass (the scale at which quantum gravity enters the game), then one has to hypothesize that the several correction terms cancel out to a part in 10^34 (a hundred billionths of a billionth of a billionth of a billionth), if one is to make the Higgs mass smaller than a lead brick.
To see how likely that is (and here is the part where you get to touch things with your hand), he proposes you to do the following experiment: ask 10 friends to tell you a random number of their liking between -1 and +1, but make it a irrational number. Then, add the ten numbers. How likely is it that you come up with a number as small as 10^-32 ?
I happen to know the answer: it is the hell of a small chance.
Michelangelo’s point is that you would rightly conclude that your friends played you a trick, and agreed in advance on the numbers they’d give you!
And that is what theorists think too: theorists feel that the accurate cancellation of Higgs mass corrections cannot be an accident.
The naturalness problem thus becomes the basis to discuss what solutions appear to make things more credible. All these solution have a thing in common: they tie the Higgs mass to some symmetry that protects it against the quadratic divergence drawn by the Planck mass scale.
If you read this post up to here, you are strongly advised to jump to his talk… No point for me to report more of it, adding to it my own fallacies.
Steven Hawking at large April 27, 2007
Posted by dorigo in humor, news, physics, science.24 comments
They say a picture is worth a thousand words…. The one below, showing Steven Hawking fluctuating in zero gravity, was taken during a B-727 flight which took off from Cape Canaveral yesterday.
At a trigger meeting 15 years ago… April 27, 2007
Posted by dorigo in personal, physics, politics, science.6 comments
David asks me to recall the story behind the famous sentence uttered by Melissa Franklin at a CDF trigger meeting 15 years ago. I comply below. By the way, I have to clarify here that I admire Melissa as a very brilliant physicist and I love her - so if you are looking for anything against her here, look elsewhere.
Anyway. 15 years have passed, but I do remember the whole thing quite well, since at that very meeting I gave my first presentation ever in CDF - also, my first presentation in English (which I did not speak fluently back then). To tell the story, I need to provide you with quite some background information below… Read at your own risk.
Mixed nuts April 26, 2007
Posted by dorigo in Blogroll, humor, internet, italian blogs, news, science.12 comments
A few disturbing links follow.
- Jeff reports of someone who does not believe in Einstein’s equation E=mc^2, claiming it was never proven, and that Einstein’s work was used to confuse matters and allow the US to gain a lead in the construction of the bomb. My goodness, maybe we should carry a gun for personal defence after all, with all these deranged individuals around….
- Angry Physics discusses the equation string theory = bush lover. With disturbing sidelines on the use of fetuses and the study of Calabi-Yao manifolds.
- Dave Bacon finds out he is obsessed by nihilism.
- Alex Janssen decides the right use of the windows over his computer screens is to host vases of chili.
- Lubos Motl discusses the Jovian atmosphere, asking the rethorical question: “Should the predicted number of exo-women of color in this environment influence the selection of the right compactification before we actually count them?“
Protons or antiprotons ? April 26, 2007
Posted by dorigo in physics, science.6 comments
I received a question which I think should be in the “FAQ” of CERN - I think the answer belongs to an independent post, for the benefit of those who never bothered to think the matter over.
So I am curious. Why does the tevatron collide protons-antiprotons, but the LHC goes for proton-proton? This has been puzzling me for some time, and even google has no anwsers
Running protons against antiprotons has the advantage of allowing one to use the same magnets to bend both beams, circulating in opposite directions, in the same way. The Lorentz force experienced by a moving charge in a magnetic field changes sign once for the opposite direction and once for the opposite charge, and the net effect is null, so that both protons and antiproton can travel in the same beam pipe - thus saving magnets, vacuum structures, and a lot of infrastructure.
So, what is the drawback ? It is that producing antiprotons is a maddeningly hard task. You produce antiprotons by smashing protons against a target, and sifting through the emerging bodies downstream, with magnet optics that select them and patiently direct and store them in an accumulation ring.
The art of producing antiproton beams has been perfected at the Tevatron in the last twenty years, but it is just impossible to reach the intensity required to achieve the rate of collisions that CMS and Atlas at LHC need in order to investigate very rare processes. Producing a proton beam is easy: you take hydrogen, strip electrons off, and there you go…
Finally, one must mention that colliding protons versus protons is not exactly the same thing as colliding protons versus antiprotons, as far as the physics output is concerned. Strong interactions do not care whether the projectiles are particle or antiparticle: what they care about is the color charge of quarks and gluons, which is the same in hadrons and anti-hadrons. But electroweak interactions do, because they are sensitive to the flavor of the quarks (electroweak processes do not “see” the gluons, by the way). So the relative rate, and kinematics, of electroweak processes is different at the two accelerators. In any case, these are details, and one can discover pretty much the same things one way or the other.
To summarize: deciding on protons versus antiprotons at the Tevatron at the end of the seventies was -as far as I understand it - a matter of cost versus effectiveness when a 900 GeV machine was designed. The Main Ring, a fixed-target (only protons circulating only in one verse) 400 GeV synchrotron which had helped discover the Upsilon mesons and the bottom quark at the end of the seventies, could be used to run hadron-hadron _collisions_, provided one injected antiprotons in one way and protons in the other. This yielded the possibility to try and discover the top quark without a complete redesign of the machine (although, well, major upgrades were needed anyways).
On the other hand the LHC, being a totally new machine, was instead built with two separate beampipes, and separate magnets in the bending tracts, thereby allowing proton-proton operation, with intensities that will exceed by two orders of magnitude those of the Tevatron - and allow to study 100-times rarer processes.
Triggering on green frogs April 25, 2007
Posted by dorigo in humor, personal, physics, science.12 comments
You think physicists like to talk with formulas and complicated lingo ? Think better. You should have followed today’s meeting on high-level triggers for CMS, at the underground conference room of building 40.
The speaker was discussing triggering strategies for collecting multijet events. Basically that has to do with the thing we call the “Trigger” (ok, yes, some lingo here): a complicated set of filters that select the 100 or so proton-proton collisions worthy of being recorded to tape among the 40 millions happening in the core of the detector every second. The decision is based on the characteristics of the event as they can be inferred through a extremely fast reconstruction. Our data acquisition system cannot record more than about 100 events per second, and sadly, the rest has to go.
Because of its potential of throwing away whole categories of interesting events for the benefit of others, the trigger is a very sensitive issue, determining what physics one will be able to do and what will not be done because of the lack of a specific filter selecting the relevant data. In 15 years of particle physics, I have never seen people fighting, calling each other names, discussing philosophy, or just acting funny as in trigger meetings. An example ? Melissa Franklin’s famous “F*** everybody” wish before walking out the door, at a CDF meeting in 1992 when her favorite dataset was being penalized by raised calorimeter thresholds.
Ok, back to CERN. During today’s talk, a question from the audience sparked a lively discussion on the design details of the triggers collecting jet events. You would think you stand no chance of following the discussion, right ? Well, you could have, since at one point people stopped using technical language and started talking funny. Here is a rough account of the discussion:
“… So, to make it clear: if you filter the event at level 1 because you see two jets and a green frog, you better be sure that at level two you require the presence of the same green frog, at the very least.”
“Yes, but I am still free to require two green frogs at level two, can’t I ?”
“Sure, two green frogs are fine. But beware, at level two you will not be allowed to require two yellow frogs.”
“Ok, but what about more than two jets and a yellow frog then?…”
The discussion went on for quite a while until people from the audience (including yours truly) started suggesting scenarios with lizards and other creatures. These kinds of exchanges are not uncommon during the long meetings of the “Physics Days” of CMS… I should come here more often!
New meaning to the word “compact” April 24, 2007
Posted by dorigo in news, personal, physics, science.2 comments
CMS stands for “Compact Muon Solenoid”. It is one of the two giant detectors being assembled as we speak inside two of the six caverns crossed by the Large Hadron Collider, the 17-miles accelerator lying four hundred feet below the pleasant ground of France and Switzerland, near Geneva.
Compact is a word one nowadays hears a lot in advertisements of electronic gizmos, cars, and the like. It is a concept which arises the pleasant feeling of something self-contained, easy to store, non-cumbersome, elegant. You want it compact, be it a cell-phone, a digicam, or a city car. Compact is fashionable, compact is practical, compact is cool.
Yet compact, for CMS, means something slightly different. I went down the pit of the Cessy site at P5 this evening, and I saw the beast with my own eyes for the first time, after years spent learning about the subtleties of its design on scientific papers and technical design reports. I tell you, CMS is not compact the way you know compactness.
No, it is not easy to store -you’d need a 20 by 50 meters pocket for that- and it is more cumbersome than almost anything else I know. But it is certainly elegant, and in some peculiar way it is also self-contained.
I was deeply impressed by touching with my hands the silvery central superconducting magnet, which while enormous, it is dwarfed by the surrounding muon detectors. Indeed, what is allegedly compact is the solenoid, if compared to the rest of the detector. The helium-cooled structure houses 20,000 ampere currents, and produces a field of 4 tesla in the tracking volume.
What impressed me most, however, was to read between the lines of what stood in front of me the incredible engineering achievement of putting together this giant mass of steel and electronics, the handling of 20 kilo-ton pieces to be lowered with millimetric accuracy into the pit. There was beauty in the construction work. Marco Zanetti, a colleague who brought me downstairs, mentioned that the cool colors I saw were actually meant to be a code: red is magnet steel, green is infrastructure where it is possible to walk, yellow tags parts needed for moving the structure, and so on. The complex really made a terrific view.
During my tour I could take a few pictures. Feeling no shame, I resembled a Japanese visitor in Piazza San Marco while I aimed my pocket digital camera at the giant pieces already assembled in the cavern, or waiting to be lowered down the pit in the assembly building above ground. And while I did, I was thinking at what I would reply if asked why not to use the official CERN pictures of the detector. No, I did not take part in building this one. Yes, I am awed by it. No, I feel my image of scientist is not harmed if I take some pictures. I have kids too, you know…Science: It’s just my job five days a week [D.Bowie, "Rocket Man"].
So here are a few pictures, taken by yours truly this evening.
Here I am, in the LHC tunnel, next to the beam line. I do not particularly fancy wearing a helmet, but you have to compromise fashion for safety sometimes.
And here is one part of the LHC triplets of low-beta quadrupoles. This guy did not suffer damage during the test of last month, but it will still need servicing to improve the lateral supports and the resistence to longitudinal stresses. Its twin, sitting on the opposite side of CMS, is the one that got damaged.
This is the pit seen from the cavern. It looks like a small hole, but the whole CMS detector has to come down that hole, piece by piece- and the smallest pieces are 17 meters wide.
Here is a view of the cavern, with part of the detector already installed. Presently, the wedges of the central electromagnetic calorimeter are being inserted, using the red structure resembling a toy for guinea-pigs. The red crib rotates, allowing insertion of the costly wedges one by one. The wedges contain the famous lead tungstate crystals that allow a precise measurements of high energy photon showers, giving CMS the capability of detecting the super-rare decay of Higgs bosons to photon pairs, among other things. In the picture, you also see the silver cylinder of the central solenoid.
And finally, here you get a nice view of one of the sections of muon drift tubes, sandwiched by the red magnetized iron. This section is still above ground, and it will be lowered in the pit later this year.
