Unclear physics

I was reading a book called “The Revenge of Anguished English”, and although the content doesn’t live up to the promise suggested by the title, there was a nice physics typo mentioned near the end: “He got his degree in unclear physics”. The question is whether that tiny letter substitution makes that much difference to most people who might be reading a newspaper biography of someone. Are nuclear and unclear synonyms to everyone who doesn’t have a physics degree? I would guess that for all practical purposes they could often be interchanged. I don’t want to be snobbish about it – I’m sure that I wouldn’t blink at an article about”More sculpture” when it was meant to be about “Moore sculpture”. Perhaps nuclear physicists should be upfront about it and just go with it. An “unclear power station” sounds quite aesthetically pleasing, as if it faded into the background on sunny days. And at least G.W. Bush could talk about such an entity without inducing a snigger from every science graduate (and indeed every literate person) in the English-speaking world.

Ferrofluids

You know, I love my work, but there are days I wish I did physics with cooler demo-potential.

Mistakes Abound

I wasted four hours last night bughunting something weird in my analysis code. It’s silly, so I’ll spare you the details.  I spent four hours watching variable addresses magically and erratically change, then gave up and asked Eric(office next door.)  He walks in, patiently listens, and points out the problem in under a minute.  Thanks, yo.  He was really humble, saying that he didn’t even understand what the code was doing.  All I needed was the perspective of someone who wasn’t on the verge of seething murderous foaming rage.  It never ceases to amaze me how sometimes someone with no experience with the particulars of the problem is the best person to solve it.

During my bughunting, I realized I needed to take a break to avoid taking an axe to my workstation.  To use the time  constructively,  I was (re(re(re)))writing the introductory part my thesis.  This is hard, because I’m supposed to sum up the history of particle physics in two paragraphs to sound like a linear, errorless set of discoveries which culminate in my Ph.D.

I found out that John Dalton got the chemical formula for water wrong: he though it was HO.  Can’t be right all the time, eh?  Here’s a nice historical overview of the development of the periodic table which is helpful if anyone needs to write an intro section.  The best part is it shows you many of the blind alleys that happend along the way.  This is real science.  100 people trying, 100 attempts, and maybe only one is the least wrong.  Dalton also believed that atoms pack like hard spheres, that their size was proportional to their mass, and that gasses were made of individual atoms.  This didn’t mesh with the work of Gay-Lussac and Avogadro, but because the whole atom thing was clearly a good idea, people wanted to believe these things too. “…the full acceptance of the atomic theory and Avogadro’s Law took almost 50 years.”  Life goes on and empiricism plus self consistency is a narrow path.  I wish they could teach science this way.

Who actually has 600 buddies?

Cheers to Julia for pointing this paper out to me: Planetary-Scale Views on Instant-Messenger Network,  Its nothing exotic, but what a data set:  They had access to the compete MS IM dataset, modulo individual identifiers.  They think they got half of all the conversations during the study.  30 billion conversations, 240 million distinct users, unless you assume a significant number of multiple accounts and robots, which I don’t think was addressed.

They get lots of broken power laws (yawn), and estimate the average degree of separation is 6.6, (double yawn), or that people in the 20s-30s are over represented with respect to the world population (ZZzzz…).    There is cool stuff though, like inter-gender conversations last longer on average than single-gender, and there’s some weird off diagonal nodes on reported age correlations or participants. There’s a cool map of users per capita of the world, and you see a significant asymmetry in the US, with more users per capita in the western half as in the east, with about the same density as in Australia.  This is clear anticorrelation with population density, but it looks cool.  People in Arabic nations seem to have significantly long conversations on IM, why this is is not immediately obvious to me.

There’s some weird extremities of the dataset: The tail of the AddBuddy events distribution shows that some people actually have 600 contacts (the maximum) on IM.  Wild.  This smells like robots to me.

Progress in QCD Pheno for RHIC?

Awesome. I love it when people do good old-fashioned straight-up QCD Pheno. RHIC sees tons of cool effects where the theory just can’t cut the muster, so I get really excited when someone hits QCD head-on, instead of doing something easier, or unfalsifiable.

So I just read this paper this morning, which basically extends DGLAP parton showering to include iteractions with Quark Gluon Plasma. This is pretty cool, as that it seems to qualitatively reproduce some of R_AA supressions. Sad thing is they neglect the reaction of the medium, so I doubt this will describe the mach cone, which is one of my favorite things out of RHIC. Can’t have it all, I guess.

In case you’re wondering, RHIC is a versatile collider on Long Island, which collides combinations of protons, deuterons, copper ions, and gold ions. The goal is to study lots of processes, but most significantly to create really hot, dense conditions where we may be able to observe a phase transition in QCD to something called the quark-gluon plasma. Maybe we already have seen it, but the theory is wicked hard, and no one is certain whether there’s really a phase transition or not. Whatever they are making, the “medium” is hot, dense, and is pretty much in thermal equilibrium as its expanding. They also know that it smears hadronic information, but electromagnetic stuff passes through unscattered. The hadronic smearing I’m talking about seen in the R_AA plots, which are ratios of stuff from gold-gold and proton-proton collisions. The basic idea is, there’s a hard scatter in pp or AuAu which are essentially the same, the energy has to pass through the medium in AuAu, and the distributions are really different. You can read more here from the STAR collaboration. The mach cone thing I mentioned is a hunch that people are seeing something analogous to a sonic boom as partons traverse the medium. This is fantastic, because if you can measure a mach cone, you can measure a speed of “sound.” If you can find a place where the speed of “sound” suddenly changes, thats pretty good evidence for a phase transition, which is the name of the game. Heres some slides of a talk I saw at DIS last year. Its a good introduction and overview to RHIC.

Multivariate Salad Bar

For those of you interested in pattern classification, machine learning, etc, there’s a really nice package called TMVA, which contains a ton of multivariate techniques which are fairly easy to integrate into High Energy Analyses, as they are a ROOT extension. Even if you don’t do HEP, they’re nice because all the methods have comparable inputs, so you can test tons of different ones without a big development hit. I’ve only futzed with the Multi-Layer Perception package, but that was pretty quick and painless to implement. A buddy of mine at H1 used it for electron tagging, and tested like seven different methods before settling on a Boosted Decision Tree. I mention this now, because Anselm Vossen just released a couple of lecture notes (I think they’re from the CERN Computing School) on the principles of some of the implemented techniques specifically Support Vector Machines and one which has a nice discussion of data preprocessing for MVA. If your shopping for selection criteria, check em out.

That reminds me, a reader “A. Game Coder” commented before that they’d like to see more posts on computing in Physics. While I’m thinking about it, check out the slides from the CERN summer school in 2006 and 2005. Lots of fun stuff like genetic algortihms and management of large data sets.

Recent Events From Space

In the last few days, there’s been a few interesting surprises in Astrobiology/Astrophysics:

Cassini has confirmed that the surface of Titan is shifting fast, and in a really weird way, which could indicate that the whole surface is floating on top of liquid, ie an ocean. This is a big if, but Titan has always been a favourite speculation for extraterrestrial life anyways, since it’s surface has lots of water ice and simple organics like methane and ethane. It also has surface lakes of methane, which could support life. But if you live in a methane lake, its living, but can you really call it a life? This was all postulated before from satellite data, but since the atmosphere is so thick, so they made these passes a big part of the Cassini mission. Cassini will make its closest pass on Titan on March 25.

Meanwhile, Hubble confirms methane on the atmosphere of an exoplanet, which is getting sexed up by the media as potential extraterrestrial life. The Interviewee for New Scientist stressed that this planet is too close to its sun for what we would call life, but its interesting from the standpoint of planetary models. This planet has way more methane than we would expect from something of its size, indicating that we don’t really understand planetary formation so well.

Lastly, yesterday the SWIFT observatory detected the brightest recorded Gamma Ray Burst ever, with an afterglow in the visual spectrum bright enough to be seen with the naked eye. What’s really cool is that it had a red shift of 0.94, which makes it the most distant object ever observable with human vision alone. The new record is now 7.5 billion light years away, and the previous winner was 2.9 million. They also state it was the most luminous object ever recorded by humans, being “2.5 million times more luminous than the most luminous supernova ever recorded.” It also has the most superlatives attributed to it, like, ever.

SUSY QCD/Seiberg Duality Reading List

The supersymmetry club is hitting Seiberg Duality this week! In preparation, I’ve been rereading the very good Argyres notes (here linked is strictly the ‘96 Weyl spinor version; If you want the Majorana version, I might ask you, why do you like unhappiness and pain, sir (or madam)?), and also the book by Terning (which I find less helpful on first reading, but very beautiful once I sort of know the stuff already).

 I also tonight started reading these notes by Strassler, which (though I’ve only read the first fifteen pages or so) are freakin’ incredible!  Why did nobody tell me these notes were so good?! (Answer: Tom and Qudsia have been telling me to read these notes for weeks now). For those who mournfully don’t know about the beauty of Seiberg Duality, there will surely be an explanatory post to follow. I seem to use lots of parentheses in my posts…. 

Open House

Today marks the beginning of the MIT Physics Open House. For anyone who has not had the pleasure, this is a couple of days where a graduate department flies out the students who have been admitted to the program in an effort to recruit them and show them why they should choose one school over another. At MIT, it is a two day event with about 70-80 visiting students.

For the current grad students it means that we get a lot of free food and are treated really well (cuz they want us to tell prospectives that they should come here). I like the open house but I also find that it stirs up a moral quandary for me. Prospective students want to know what grad school is like. They ask probing questions and sometimes it is difficult to answer them. I can never decide how much truth to give them.

The truth about grad school is that it is not always a good time. (Dave is going to hate me for saying this.) In fact, often times, it is frustrating, exhausting, stressful, and downright unpleasant. And maybe for weeks or months at a time. I think most of us wake up at least once and ask ourselves if it is really worth it. I know that I thought seriously of quitting at least 9 times. Most of us stay and finish our PhD’s for some reason or another. But a lot of us end up pretty unhappy at one point and somehow get through it. And to be really honest, you don’t go to grad school at a place like MIT because it seems ‘fun’. Just like you don’t live in Boston for the weather.

I didn’t realize it when I started, but your life happens while you are in grad school. Six(ish) years is a long time in your (most often) mid-twenties . A lot can happen… you can get married, have kids, fall in love, fall out of love. You can get sick, get healthy, run a marathon, lose a parent, buy a house, discover who you are, change who you are, develop your professional life, ruin your professional life, gain weight, lose weight. Life happens. These things occur whether you are in grad school or not. I think the one thing that makes grad school different is that the reward comes at the end. You spend six years working for very little money on a project that may or may not work out and in order to reap the rewards, you really have to stay for the whole thing. You aren’t as able to cut your loses and boogie on out half way through because you don’t get the degree that way. Then you have three years of effort without anything to show for it.

I know that I didn’t understand this when I started grad school. I didn’t know what exactly I was getting in to. As I get closer to graduation, I am glad that I decided to stay and finish. But I still wonder at what cost? What else would I have done with my mid-twenties?

Open houses are a great opportunity to explore a grad school program, but it is difficult in two days to really get a feeling for what life will be like in a program. There are lots of questions and lots of very different answers. You come in wanting to ask good scientific questions and find an adviser to work for but it should be more about making sure the place is somewhere you want to be for a long time while both amazing and terrible things will happen in your life. If you happen to be going to an open house, good luck and ask tough questions of both the grad students and the professors. Oh, and don’t forget to have a good time!

The immodesty of physics

Well, I suppose that I should take Dave up on his invitation to reveal all about “the saddest missed opportunity in science popularization, ever. “ .   And he was indeed very sad at the time.    Almost in tears, in fact.

Our story begins almost three years ago in 2005, labelled the “International Year of Physics”.   I was involved in a bmx stunt to launch this year  (the Einstein Flip) and so for a while my name was in the media a lot, and if you’d been looking for a random physicist you’d have found me.     A month afterwards, my office mate took a phone message for me from “the PR company for Cirque du Soleil”, which was a respectable start.   I phoned them back, and spoke to someone who wanted a physicist to get involved in publicising a performance.   They were a bit cagey about exactly what sort of performance it was, so I told them that I’d need to know more about what it was before I committed to getting involved.     They said that they’d send me an e-mail, rather reluctantly.   The e-mail finally arrived.   They wanted to publicise Immodesty Blaize, a burlesque dancer.    You can look her up – I’ve since heard her on the radio, talking about the serious side of her act (to do with how women are perceived in society).    I think that the act itself might have involved a reverse strip-tease (putting clothes on in a sensual way, rather than taking them off).  Anyway.   The e-mail said that one of the major features of her act was that she could make her nipple tassles rotate in opposite directions at the same time.   In order to promote her act in the newspapers, they wanted a physicist to “do some experiments” associated with the physics of this process, and then splash this story across all the papers in the UK.   The papers that they mentioned were the sort of newspapers that go in for sensation and headlines that take up half the page.   The e-mail finished with an offer of ten free tickets to one of her shows and an invitation to come and meet her and “get a feel for what’s going on”.   I kid you not.  Those were the words used.     The e-mail also included a picture of Immodesty and her sidekick Walter (who was wearing a very fetching bowler hat).

So.   I have talked about a lot of physics to a lot of people.   I believe that you can’t dictate to people what they should and shouldn’t want to pay attention to – you have to engage them with something that genuinely interests them.   Physics is never mentioned in this sort of newspaper.     On one hand, it would be a great opportunity to show readers of such papers that there are female physicists out there and to demonstrate how relevant physics is to everyday life (not that I counter-rotate my nipple tassles every day, cough)  On the other hand, it’s very much just cheap publicity without any real substance, very frivolous.    It’s not that physics can’t be fun, but you don’t want to cheapen it.

The way the e-mail was written was a little bit odd.   I still wonder whether it was a practical joke – if so, it was an exceptionally good one.  On balance, I think not – I think it’s just that the person who wrote it only scraped a pass in their English exams.   Immodesty’s website did have a cartoon of her with nipple tassles, and when you moved the computer mouse over them, they rotated faster and faster (and in opposite directions, of course).    Male friends of mine were amazingly fascinated by this – it’s in the top ten best ways I have ever seen of keeping a bloke quiet.   I spoke to the PR people on the phone again.   In the end, I told them that if they wanted to do spoof physics, they should get a spoof scientist.    Dave cried because he was not going to get one of the free ten tickets to her show (and I had a lot of male friends who altruistically volunteered to help me make use of those tickets).

But the whole story raises some interesting questions.   Was I too shy or too stuffy?   Should I have seized this opportunity to get physics and physicists some free publicity and to show that we’re not all non-human nerds in white coats?   It wouldn’t really have done me any harm, although I suppose it would have been a joke among all my friends for a very long time to come.   Physicists have to be approachable.   Nipples are apparently very approachable.    What do you think I should have done?

p.s.   Something interesting that came out of this is that when you tell this story to females and you look very carefully, you can quite often see them moving their shoulders a bit, as they’re subconsciously wondering how the counter-rotating nipple feat is achieved.