Search Results for: rhic

ALICE Publishes!

Jacques Distler pointed out that ALICE has just published their first paper, only a little over a week after the beginning of the heavy ion phase of the LHC at CERN! Moreover, they are way ahead in energy of the previous heavy ion collision experiment (RHIC) and have verified “elliptic flow” (the main sign that the quark-gluon plasma behaves like a strongly coupled fluid, the big experimental surprise of some years back, with properties of a type that can be nicely captured using string theory models). Have a look at Jacques’ post here, and go directly to the paper of ALICE here.


Please see my post from last week (“Experimental Excitement” was the apt title) about why I’m excited about all this!

-cvj Click to continue reading this post

Experimental Excitement!

alice_frist_run_dataWell, this week is a big week, in some ways. The Large Hadron Collider has gone into a new phase! For a while, the experiment has turned aside from the task of searching for the origin of mass (the Higgs Particle, or whatever it is that mediates the generation of the masses of elementary particles – see earlier posts, and features like this, etc) and is turning to heavy ion collisions. Rather than studying processes in which only a few particles at a time are interacting at super-duper-uber-high energies, the experiment will instead collide together the nuclei of lead atoms, so that you get lots of particles colliding together and creating a messy “soup” of high energy stuff all together. The goal is to understand the constituent nuclear particles (quarks and gluons) working collectively at high temperature (and low to moderate density), instead of focusing on issues concerning individual fundamental particles. Today (starting late yesterday, actually) is an exciting day because it marks the first step on the journey to probe deeper into this physics. The ALICE experiment has started looking at these collisions. See top right for some screen-shots of the mess of particle tracks that are left after the soup flies apart. The trick is to analyze all these tracks from millions of such collisions to work out the properties of the soup.

As you perhaps know from reading this blog, while of course I’m interested in the behaviour of fundamental particles and the origin of mass, and so on and so forth, I’m very interested in this nuclear issue too. Some of the most interesting work that […] Click to continue reading this post

Other Accelerator Physics is Available

The alternative title for this post was going to be “Closing in on Unobtanium”, but I realized that it might be better to explicitly remind you that the Large Hadron Collider, understandably featuring in the news a lot these days, is not the only particle accelerator in operation. Such machines are routinely at work all over the world (for example, supplying hospitals with radioactive materials used in medical diagnosis), and doing various kinds of key research (recall as another example the RHIC physics I’ve told you a bit about in relation to certain applications of string theory). One such set of investigations involves finding new heavy elements, extending the periodic table of elements. Yes, just like happened with Pluto’s demotion and its resulting effect on your internalized list of planets in the solar […] Click to continue reading this post

The Universe: Cool Cars, Hot Sand, and Fast Balls

flows in death valleyYou may recall my mentioning a desert trip to shoot something for TV, some time back. One done at precisely the wrong time of year. And to Death Valley, one of the hottest places on earth, to boot. Well, I meant to mention that the episode of the History Channel’s The Universe that the shoot was for aired a week or two ago and it was really excellent. It was entitled “Liquid Universe” and it was a rather beautiful and thoroughly pleasant episode exploring the role of liquids in our universe, a matter not often raised in questions of astronomy except when it comes to matters of water from time to time. This was not about water per se, but rather the whole matter of material that flows and the role it plays in diverse areas of the solar system and perhaps the universe at large. I was using sand to demonstrate how sometimes there are surprising places where you can find fluid/liquid behaviour, and mentioned some of the new phases of matter found in the context, for example, of quarks and gluons at RHIC. (I’ve spoken about that here a number of times in the context of some of my research. See the archives.)

It was an excellent episode and another example of how one can take a topic under the “The Universe” heading and showcase lots of exciting science quite accessibly […] Click to continue reading this post

News From The Front, VII: What is Fundamental, Anyway?

One of the words I dislike most in my field – or more accurately, a common usage thereof – is “fundamental”. This is because it is usually used as a weapon, very often by people in my area of physics (largely concerned with particle physics, high energy physics, origins questions and so forth), to dismiss the work of others as somehow uninteresting or irrelevant. image by I don’t like this. Never have. Not only is it often allied to a great deal of arrogance and misplaced swagger, it is often just plain short-sighted, since you never know where good ideas and techniques will come from. A glance at the history of physics shows just how much cross-pollination there is between fields in terms of ideas and techniques. You never know for sure where valuable insights into certain kinds of problems may come from.

Fundamental physics is a term I used to hear used a lot to refer to particle physics (also called high energy physics a lot more these days). This was especially true some years back when I was an undergraduate in the UK, and it persisted in graduate school too, and is still in use today, although I think it is declining a bit in favour of less loaded terms. Somehow, a lot of particle physics is regarded as being all about the “what is everything made of at the very smallest scales” sort of question, first discussing atoms, and then atoms being made of electrons surrounding a nucleus, and the nucleus being made of protons and neutrons, and those in turn being made of quarks, and so on, in this was arriving at a list of “fundamental” particles. There’s the parallel discussion about the “fundamental” forces (e.g., electromagnetism and the nuclear forces) being described in terms of exchanges of particles like photons, gluons, and W and Z particles and so forth. There’s no real harm in the use of the term fundamental in this context, but this is about where the word gets elevated beyond its usefulness and starts becoming a hurdle to progress, and then a barrier. Somehow, “fundamental”, meaning “building block” gets turned, oddly, into “most important”. The issue of what the smallest building blocks are gets elevated to the most important quest, when it is in reality only a component of the story. It is rather like saying that the most important things about the Taj Mahal are the beautiful stones, tiles, and other components from which it is constructed.

Perspectives have evolved a bit since my salad days, with the rise of wider […] Click to continue reading this post

Some Articles

Well, as I mentioned in the last post, Sunday’s symposium at the AAAS meeting in Chicago went very well, and we successfully communicated a lot of the physics results, ideas, and excitement to the audience. One of the team, Peter Steinberg, did a blog post, and he’s also got some more pictures that you’d perhaps like to see.

Some of the journalists who were there have already produced some pieces reporting on the physics. It is actually interesting to see all their different takes on the same presentation and discussion event. So far, I’ve seen the one by Glennda Chui at Symmetry Breaking, which had the mixed blessing of being tagged by Digg (the server was down for hours as a result!), one at Physics World by Margaret Harris (this one sort of missed the key physics point a bit – see below), one at the Discovery Space Blog by Dave Mosher, and one by John Timmer at Ars Technica (He misquotes me a little here and there, but I do like the “String Theory Officially Useful” phrase in the title!). [Update: There’s also an AAAS publication here.]

Anyway, as I said, I think that the Physics Today one sort of got sidetracked a touch and so I placed a comment there to clarify some points. I realized that they might be useful to some reading here, and so I reproduce it here. Enjoy: […] Click to continue reading this post

24 – Physics Edition (Day Two)

February 14th 2009: Valentine's Day.

9:00pm – 10:00pm

…Must be here somewhere. Maybe inside the monolith? No. Seems it is not inside the jumbo suitcase, which I have not used since Aspen last year anyway, and I’m pretty sure that I did not use it on that trip. Where can it be? That box over there? No. (But I found that bag of plastic book covers that I’ve been using sparingly since I left Preston for London in 1986. Excellent. The things I don’t throw away…) Well, never mind, would be silly to make myself miss a flight over an inflatable pillow that I have not seen in over a year. If I play my cards right, I won’t need it anyway….

9:10pm Now to put all those things I set aside earlier into my trusty little day trip bag. Change of clothes, electric shaver, toothbrush and so forth. I suppose I will bring the laptop. And some bits of equipment that might be useful as backup for Peter’s plan. Or whatever. You never know. Yes, I throw in my copy of Accordion Crimes. Almost finished it, and if I do, would be good to get another Annie Proulx to continue enjoying her wonderful writing…

9:17pm Will someone tell me how I managed to be perfectly on time, and then fritter away some of it to make sure I’m slightly panicky late again? Sigh. I was more or less ready at 9:00, when I should have left. Despite all the events of the previous 24 hours ((Day One) – Valentine’s Day Diary – Available on DVD) I got everything together on time, and wouldn’t it be rich if I missed the flight?

9:23pm I leave finally, using the batcave, slowing to check that entrance closes, then vanish into the night toward the airport. Saturday night late in LA. Surely everyone is out having awkward dates? The roads will be clear this late on a Saturday night, right? I can make my 10:07 check-in cutoff, I’m sure.

9:33pm. 101 Freeway. Full of traffic. Don’t you people have dates you’re supposed to be on!!?? This is my road! My! Road! […] Click to continue reading this post


Yes, I’ve been a bit quiet of late, I know. I’ve so many things on, both professional and personal that it sometimes keeps me occupied from when I wake up just before sunrise right through to falling asleep a bit after midnight. And yes I know that means I’ve been not getting the traditional full nights of sleep, but if my body insists on getting up at 5:30am, who am I to resist? I thought it was due to jetlag from the trip a couple of weeks ago, but it seems to have taken. I don’t mind too much since watching the light change as the sun rises is a marvellous way to start the day.

clifford johnson preparing slides at the boardAmong the things I’m up to (yesterday and today so far) is a strip-down-and-redesign of a short talk for an exciting symposium that is coming up in a few weeks in Chicago. The American Association for the Advancement of Science is having their big annual shindig there (apparently the biggest science conference in the world) and there will be a number of addresses, plenary talks, and keynote speakers and the like (including Al Gore, by the way), and also several sessions of symposia and other presentations on various topics.

While slightly annoyed at the fact that one major day of the conference is on Valentine’s day (which means I’ll have to be out of town on just the day that maybe, just maybe, on the off-chance, you know – if the universe sneezes or something, somebody might want me to be their Valentine…*), I was looking at that day’s schedule and it caught my eye that there’ll be a session (with several presenters) entitled “The Science of Kissing”, and three hours long, no less:

[…] Click to continue reading this post

Atoms and Strings in the Laboratory?

depiction of lithium trap from the Kastler Brossel lab in france

A depiction of a lithium trap from the Kastler Brossel laboratory, in France. Details here.

[Despite appearances, I did not choose the music in what is to follow. I just put on iTunes set to random, and started typing, reporting on what was playing as I went along. Nevertheless, there were some nice resonances.]

Now playing: Mr Day, John Coltrane.

So. I must put the Aspen time on hold for a short while, as I promised to give four lectures in Vancouver starting tomorrow. While I sit here in a lounge in Denver at 8:00am, wondering why I booked a 7:00am flight out of Aspen, and also wondering exactly what is in this muffin that I picked up to have with the (rather good) tea they have here this morning, I thought I’d tell you about a little bit of really nice physics that’s going on in the neighbourhoood of my world. Since I’m too cheap and too disinterested to pay for a connection to the web, this’ll only get uploaded quite a bit later when I get a free hookup. (This is a bit more technical in places than usual. Please don’t give up too easily. Oh, and you might have to read some things I point to from earlier to get everything I’m saying – I’m not one for endless repeating myself I’m afraid.)

You can think of this as another story in the line of development I’ve been pushing (and telling people about here and elsewhere) for many years now. Applications of string theory to a broader range of physics areas than the popular discussions of the topic seem to touch upon. I told you last year about the exciting work going on in understanding properties of new phases of nuclear matter being unlocked at the Brookhaven experiment RHIC (colliding heavy nuclei together to create a sort of hot quark-gluon soup). That work continues. This new work pertains to experiments as well, and this time, these are closer to the human scale bench top experiments we all get misty-eyed over (ok, I do, maybe no-one else). It is super-cute stuff. I should […] Click to continue reading this post

Frank Common Sense

Did you catch the discussion on NPR’s Science Friday just past? I was particularly pleased to hear some calm, thoughtful responses from someone who definitely knows his way around the issue, on a major broadcast. What issue? Whether or not we high energy physicists are carefully endangering planet earth (or even the whole universe) by switching on the Large Hadron Collider (LHC) later this year (or whenever it is due to start collisions). You’ll recall the lawsuit, since I posted on it here (with links to other thoughts), and perhaps you even recall my April Fool post on the matter.

Well, Ira Flatow was talking to Frank Wilczek! It was a good, informed chat around the issues that also gave Frank a chance to explain a little about what the machine was really constructed for (since this seems to so easily fall out of these public discussions of black holes and extra dimensions and strangelets (interesting as they are), and to plug his book that is due to come out. Since it’ll almost certainly be a really interesting […] Click to continue reading this post

Talk Talk

[Post reconstructed after 25.10.07 hack]:

dbranesTwo Thursdays ago I went up to Santa Barbara to give a seminar. I had a great time, and it reminded me why it can be so much fun to go somewhere and visit for even a short time and do that. I got to catch up with several old friends, including Santa Barbara itself, where I lived for a number of years in the 90’s when I was a postdoc. I spent time chatting with the various people there before (at lunch) and after (individually) the seminar, learning about some of the research they’re doing, and also talking about other matters physics-wise and gossip-wise. I wish I’d had more time to talk since I did not get to talk to everyone I wanted to talk to, and not at as much length as I would have liked. (This was partly due to the fact that I spent the morning in my hotel room writing some of the slides for my talk. – I had a presentation the day before to focus on, along with a departmental visitor to host, and the day before I was also occupied. Don’t ask about any earlier than that – I never prepare new material that much in advance. Not because I don’t want to, but it just never happens… if I have more than a day or two, I will find that there’s other stuff I have to do.)

Anyway, a good time was had by all (I think). I can even post a picture of some of us at dinner in the evening after the talk. (Will update later with that, since it was downloaded to computer that’s not here.) We went to an old haunt of mine in downtown Santa Barbara – Roy’s. I’m pleased and surprised that it is still there and going strong, since it is the sort of highly individual restaurant that – since it is also reasonably priced – you’d expect to vanish from such a high value spot in town.

What was I talking about? Well, with three students (Tameem Albash, Veselin Filev, and Arnab Kundu), I’ve been involved in some fun work on some of the physics concerning […] Click to continue reading this post

Tales From The Industry, XII – A Shooting Diary

Here’s my promised report/diary on yesterday’s adventures in film-making.

history channel shoot september6:45am Got up a bit earlier than perhaps I should have, given that I got to sleep at 1:00am. Spent a while reading a ton of email, and sending some more. Will be away from my regular professoring duties for the whole day, and so wanted to make sure the fort was held. Prepared some appropriate TV clothing (pretty much what I wear normally anyway – simple solid colours), and so forth. Attempted to beautify myself just a tad (with the usual…inconclusive results). Shower and so forth. Coffee and oatmeal, sprinkled with NPR… Read a bit of stuff on dates of historical background on material I’ll be talking about. I often forget that sort of thing, and its never ever needed whenever I do remind myself of it, so after a few minutes I decided not to bother. The core physics ideas are more important, ultimately. Spent time looking for rain gear (the micro-brolly, basically), since supposedly there’s going to be a rainstorm later (hurrah! finally!). Ready to go.

8:45am Fifteen minutes later than I intended to (how did that happen?), I set off to walk to the Sunset/Vermont Red Line subway station. Waved to a neighbour, and we exchanged pleasantries about how nice a day it was.

8:47am Walked past surprised neighbour back toward home…. briskly.

8:52am Riding the Brompton (the folding bike, for those of you not keeping up), I cycled off to the Sunset/Vermont station.

9:01am Arrive at said station on schedule (one minute late does not count in LA), and […] Click to continue reading this post

Lookin’ For Some Hot Stuff

Hot, hot, hot, hot stuff
hot, hot, hot
hot, hot, hot, hot stuff
hot, hot, hot

– from “Hot Stuff”, by Donna Summer (1979). I refer to not only the physics but the c. 100 oF temperatures we’ve been having here every day recently.

On my way back from the conference, I spotted this book (left) last Saturday in Foyles (the booksellers) in London 1. Quark Gluon Plasma book It is a collection of reprints of a lot of the papers forming the foundations of the physics of the quark-gluon plasma (QGP) idea, going back the early to mid 1970s with such papers as Collins and Perry (Gosh, I had no idea Malcolm was one of the early workers on this idea. He’s much more thought of as associated with black holes, gravity, strings and so forth, ideas which – ironically – have recently turned out to be relevant to the discussions of the physics too. See my recent post, and there are also various popular articles to be found2).

Putting aside the usual ridiculous price that Springer Elsevier charges for books, I found myself in two minds about this book, in view of the surprises being uncovered about the properties of this remarkable state of matter at the RHIC experiment. Is this collection of early papers a useful working tool, or is it now just of historical interest, since many of the basic expectations about the properties of the plasma seem now to be incorrect?

rhic collision of gold ionsWell, after a bit of thought, I decided that the latter view would be way too hasty. First and foremost, on a general level, even if some of the computations in some papers were done in the “wrong” light (it’s a strongly coupled liquid that flows, not a weakly coupled gas of quarks and gluons), much of their content will still be useful in many ways – good and correct calculations last for all time, it is the sense of the words decorating them that may crumble over time. More specifically, one can worry about whether there were assumptions (and approximations based on those) that went into the computations that will render […] Click to continue reading this post

Exploring QCD in Cambridge

exploring qcd sign

So the conference here at the Newton Institute in Cambridge is simply marvellous. I’m so glad I came, and so happy that I was invited to attend and make a contribution to it by giving a talk and having discussions. It’s a rather splendid combination of experimentalists, phenomenologists, and various hardcore theorists of various sorts, and there are ideas just flying around and bouncing off the walls. The title is “Exploring QCD: Deconfinement, Extreme Environments and Holography”, (it’s organized by Nick Evans, Simon Hands, and Mike Teper) and the focus is very much the fascinating nuclear physics of heavy ion collisions at the RHIC experiment at Brookhaven, and the experiments to come on heavy ion collisions at the LHC at CERN. The latter is an aspect of the physics to be done at the LHC that you don’t hear about much because it is sidestepped in favour of discussions about the Higgs, origin of mass, supersymmetry, theories of everything – such as strings, microscopic black holes, extra dimensions and all that other good stuff. (See earlier discussions here, here and here.)

Well, the great thing is that there’s been plenty of discussion of black holes, extra dimensions, strings, and so forth at the conference because of a great deal of promise of its relevance to nuclear physics. It’s been right alongside the discussion of experimental results, and other theoretical approaches such as work on computer simulations of aspects of QCD (“lattice QCD”) and studies involving other techniques. There’s very much a spirit of open-minded exchange among all the various parties […] Click to continue reading this post

Quark Soup Al Dente

Here’s Rob Myers in action, giving Monday’s excellent departmental colloquium, entitled “Quark Soup Al Dente: Applied String Theory”:

robert c myers quark soup al dente

Here was his abstract:

In recent years, experiments at the Relativistic Heavy Ion Collider have discovered an exotic new state of matter known as the quark-gluon plasma. Simple theoretical considerations suggested that this plasma would behave like an ideal gas, however, the experiments show that it actually behaves very much like an ideal liquid. Thus the standard theoretical tools, such as perturbation theory and lattice gauge theory, are poorly suited to understand this new phase. However, recent progress in superstring theory has provided us with a theoretical laboratory for studying very similar systems of strongly interacting hot non-abelian plasmas. This surprising new perspective extracts the fluid properties of the plasma from physical processes in a black hole spacetime. At present, this approach seems to provide some of the best tools which theoretical physicists have to understand the heavy ion collisions at RHIC.

For a very good blog post on this issue, see Bee and Stefan’s post at Backreaction.

It was really excellent to see Rob and spend some time with him at dinner afterwards and at lunch the next day with my students. We got to chat over a nice Tapas-style meal and catch up a bit on what each other has been up to (both in and out of physics – Rob is one of my most long standing friends and collaborators in the field), and he even gave us a seminar on Tuesday before leaving.

Now, here’s a physics question for you: […] Click to continue reading this post