Category Archives: research

SCSS San Diego

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dinner_pic_cvjFriday’s meeting was rather nice. There was a really good turnout (especially from UCLA) and so in the end we had the perfect combination of an attentive and receptive audience and four really good speakers. As per design of the whole thing, plenty of time was allowed for discussion and pedagogy, and so I got the feeling that people felt really comfortable raising points during the talks and also chatting further during the breaks and lunch and dinner. It was really good to catch up with friends and colleagues from groups in the area, […] Click to continue reading this post →

Englert-Higgs

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This morning the 2013 Nobel Prize in Physics was announced, and it was given to Francois Englert and Peter Higgs for the 1964 theory of what’s now often called the Higgs mechanism, recently directly confirmed experimentally by the Large Hadron Collider at CERN (as you might recall) by the finding of the Higgs particle. You might recall that the mechanism, also associated with the term “symmetry breaking”, is responsible for the masses of the elementary particles, as has been discussed here and elsewhere a lot. (And recall, that it has little to do with the mass of everyday objects, as people sometimes say. That’s a different matter… everyday objects’ mass is dominated by their binding energy… coming from the forces that hold them together… not the Higgs mechanism.)

The first thing to say is “Congratulations!” to the winners. It is sad that Robert Brout (Englert’s co-author) passed away before he could get the prize as well. A nice thing you can do is take a look at the actual papers that are central to the citation in Physical Review Letters right here, as the APS have made them specially available. It’s good to take a look at what the actual papers look like, to get a sense for how our field works, so go ahead. I also recommend the lovely book of Frank Close, “The Infinity Puzzle” for a very good presentation of much of the ideas and history of this and related chapters in the field of particle physics.

My own thoughts on all of this are mostly of delight, but there’s something else there as well. Without a doubt, it is great to see particle physics and the pursuit of […] Click to continue reading this post →

Different Teacup, Same Storm

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Meanwhile, poor Matt Strassler, who means well, is re-discovering the frustratingly convenient (for some) fact that blogs (or is it blog readers?) have no memory for stuff that has scrolled off the page, so attention-seekers get to make the same deliberately wrong claims and misrepresentations they did before, and that were thoroughly addressed before, and a whole new bunch of people who want to learn a bit of science will be drawn in to a non-debate, not knowing that none of this is new. Attention-seekers get the attention they desire, and since attention is the main point for them (not actual progress in science, oh no, not at all!), they succeed.

Matt is discovering this now… By trying to discuss a little nuance about what recent discoveries at the LHC may or may not mean for string theory, he has wandered into the same old tired shouting match about string theory with attention seekers who have nothing better to do but put their hands over their ears and yell misleading slogans from the sidelines to generate fake controversy, and/or split the world into pro-string vs anti-string which is so simplistic and, frankly, juvenile. An interesting game, if you’re up for it, would be to look at the noise in the long comment stream there, and then look at almost any of my Scenes from a Storm in a Teacup posts (from 2006!!!) and the long comment streams accompanying them (look at, for example IV, V, and VI), and see if you can see the same sorts of patterns. I deliberately collected those posts together to form a partial* record of some of that time’s discussion for precisely this purpose, for those who care to read and see that all attention-seekers (who have no real interest in letting science research run its course) have to do is wait for a while and then start yelling the same faux claims all over again to get attention, sell books, enlarge their mutual admiration society membership, etc.

You know, all this behaviour is hardly different from that of the annoying squirrels I have to deal with at my fruit trees from time to time. Not being so good at cultivating [..] Click to continue reading this post →

Phase Diagram

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phase_diagramFor those who have a thirst for something physics-y to follow the tomato chutney post, here’s a decorated physics diagram I made in Matlab this morning. Click for a larger view. It’s the phase diagram of interesting black hole transitions* (that I co-discovered 14 years ago) associated with part of the story I mentioned last month. On the right of the line you have small black holes favoured (of a given charge, so move horizontally), and on the left side of the line the system favours large black holes and so when you cross the line you have a sudden jump from one type to the other. That second order critical point I talked about there is the end of the line of first order points. The blue dot. Above there, you cross over smoothly from small to large holes. The blue dot is the border between the two cases.

It is a bit like having steam (or water vapour) on the left and liquid water on the right, and crossing the line is what you call boiling. The second order point is the place […] Click to continue reading this post →

Steamin’

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CPU_usageYeah! It feels great when I get the workhorse computer really chugging along. 85% is unusual to see on a normal run, since this beast (a 2010 3.32 Ghz Mac pro quad core) has a lot of computational capacity that you don’t need for most tasks. I’m getting up to 85% because all four cores are crunching away independently on the same problem (written in MatLab) but different parts of it. Each point on the resulting graph will be the result of having computed 2000 points. Each of those 2000 points comes from computing a boundary value problem discretized into a million points. See an earlier post for more about that.

(Update: Now running even more tasks associated with this problem: Up to 96% now:
CPU_usage_2
…with nothing idle at all. This is probably not as efficient any more, but it is for a few hours and then back to 85%. In the meantime, it is amusing how it makes me feel I’m doing more work somehow…)

I assigned different parts of the graph to different processes by hand, not using a […] Click to continue reading this post →

News from the Front, X: Smoother Transition

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second_order_transition_1Yesterday I submitted a new paper to the arxiv. This is is my favourite curve from it. Some of you who follow the blog will recognize the blue circle-dots and guess that this is the output of the dot-generation I’ve been tinkering away at (and reporting on somewhat cryptically) since April (see e.g. here, here, and here). Correct. There are many reasons why that is the case. One of them might well be because it looks like a very comfy chair, and by time I’d submitted the paper, I was rather tired. I’d pulled an all-nighter to finish the paper because I wanted to submit it by noon yesterday, and the night before I had to spend several hours at a social event.

So once it was an appropriate time to leave the place I was at, I said my goodbyes, jumped on my bike, pedalled home, all_nighter_things put on some coffee, some Ana Tijoux (through headphones, so as not to wake anyone. Why her? Kinetic energy was what I needed at that moment – her vocal style is full of that. Try “La Bala” or “1977”. It is in Spanish, but that’s just fine.), and from 10:30pm to about 12 hours later, ground out the paper. I had to do this since I took some time away from the research project for a week, and then on Tuesday evening noticed the title and abstract of a new paper on the arxiv that suggested some overlap with what I was doing. So I had no choice but to gather all the results I’d been gathering the last several weeks and write them up and get them out, putting off reading the other paper until afterwards, so as to remain independent. Hence the all-nighter to finish it all. It was a pretty easy paper to write since I’ve had the results for a while, knew what I wanted to say, and it was just a matter of pulling everything together and writing a lot of background to set the scene for the results. A fair amount of the time was spent fiddling with things like how to generate figures from Matlab that embed nicely into the text, and so forth. Technical tedium.

The physics? Another reason I like the above curve is because it examines physics from an old favourite phase transition I co-discovered almost 14 – gosh yes, cvj, fourteen! – years ago. To my knowledge it is perhaps the earliest example of a […] Click to continue reading this post →

Effective

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I just learned* that Ken Wilson died a few days ago (Just 15th). Wilson is another of the giants that you don’t hear much about in the popular media coverage of the great ideas in Physics that form the bedrock of so much of what we do. You still get people saying utter nonsense about “hiding infinities” in physics and so forth (often in discussions on blogs and various similar forums (fora?)) because what he taught us all about effective field theory and the renormalization group still is only taught in some advanced classes on quantum field theory (and still not as well or frequently as it should be in such classes … it has only relatively recently begun to be put at the forefront in textbooks on the subject, such as Tony Zee’s). In the cut and thrust of the mainstream of research though, I’m happy to see that so much of Wilson’s legacy is in the most basic fabric of the language we use to discuss results and ideas in particle physics, condensed matter physics, quantum gravity, string theory, and so forth.

I had the distinct privilege of having Joe Polchinski as a mentor for some of my postdoc years, who is known as being one of the current giants on the scene who […] Click to continue reading this post →

Southern California Strings Seminar

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The group at UCLA is hosting the next SCSS, and it is on Friday. More details here. The schedule looks good:

9:30-11:00 Sera Cremonini (Texas A&M): “Probing the IR of hyperscaling violating geometries.”

11:15-12:45 Ken Intriligator (UCSD): “Aspects of 3d N=2 Chern-Simons-Matter Theories.”

12:45-2:15: Lunch

2:15-3:45: Daniel Harlow (Princeton): “On the Computational Complexity of Hawking Radiation”

4:00- 5:30: Eric D’Hoker (UCLA): “Supermoduli and supersymmery breaking”

Enjoy!

-cvj Click to continue reading this post →

Something’s not quite right, perhaps?

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thing_vs_thing Yeah. Scary, right? I woke up one morning to this result (see earlier posts here, here, and here) from a night of an intensive computer run. It was not meant to be a straight line, but pretty close to it, so I knew that something was wrong with my code. Took me a good long while to trace the problem, but I did in the end. My signal was being swamped by both […] Click to continue reading this post →

Lines of Thought

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So I’ve moved on to curved lines now, in case you’re wondering. 🙂 (See previous posts.) The last several days (the research parts) have been taken up with more computations. A lot of the time has been spent calibrating the programs, and trying to assess and understand and characterize the inevitable errors that show up, by running the programs and checking the resulting plots of data points against expectations shaped by hand calculations. Calculating on the train to and from work, I’ve filled several pages of my small notebook with computations, alongside sketches of some of my surroundings as usual (people mostly). As a result (fingers crossed) I think I’ve now understood all the key aspects of the results I’ve been getting, and have good numerical control of things. To get such control, I’ve had to push the error tolerance and the size of the grid of points I’m computing on to regimes where I’m back again to waiting for the better part of an hour for each data point. (One sets up the problem on the computer by making continuous variables, such as space and time, into discrete ones, forming a grid. The problem is then to use various […] Click to continue reading this post →

A Much Shorter Straight Line

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LinePlot2 How is the line coming along? It is very kind of you to ask (if indeed you were). Well, there it is to the left. (See the previous post for background.) In the end, I abandoned Maple since it was taking way too long to do each point, and just for the simple example. (When I tried to do one sample point of the complicated example it took 24 hours and I stopped it before it was done!) The point is that Maple does not easily […] Click to continue reading this post →

A Very Long Straight Line

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I’ve been multitasking in an interesting way. Sort of. I’ve reached a certain point with some computations I am doing that I cannot go beyond by analytic means. LinePlotThis means that I can’t extract the physics I need by doing algebra and other exact manipulations on paper any more. Progress can continue however by using numerical means, employing a computer to solve the highly non-linear equations and extract the juice. There are several steps involved, and ultimately, I want to determine how a certain physical quantity depends on another physical quantity. (I’m sparing you the trouble of knowing what the details of the physical quantities are, since it does not matter for the thing I am trying to tell you. It relates to quantum field theory, gravity, and string theory, which connects the two.)

I can see that dependence quite clearly if I simply plot a graph of one versus the other, and in this case I need the computer to work out what the points on that graph are. I actually don’t know the answer for the cases I really am interested in, nobody does (that’s why it is research!), and so that’s what I want to find. I want lots of points to get a nice smooth graph, so the computer has to compute a lot of points, and I need to run it for a long time since I want it to compute the points very accurately. So I wrote a program (in Maple) to work on the problem, studying just one […] Click to continue reading this post →

TED Youth Talk – Hidden Structures of the Universe

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cvj_TED_YouthYou might recall that last year I gave a talk at TED Youth, in their second year of short TED talks aimed at younger audiences. You’ll recall (see e.g. here and here) I made a special set of slides for it, composed from hundreds of my drawings to make it all in graphic novel style, and somehow trying to do (in 7 minutes!!) what the TED people wanted.

They wanted an explanation of string theory, but when I learned that telescopesI was the only person in the event talking about physics, I kind of insisted that (in a year when we’d discovered the Higgs boson especially!) I talk more broadly about the broader quest to understand what the world is made of, leaving a brief mention of string magnifytheory at the end as one of the possible next steps being worked on. Well, they’ve now edited it all together and made it into one of the lessons on the TED Ed site, and so you can look at it. Show it to friends, young and old, and remember that it is ok if you don’t get everything that is said… it is meant to invite you to find out more on your own. Also, as you see fit, use the pause button, scroll back, etc… to get the most out of the narrative.

I’m reasonably pleased with the outcome, except for one thing. WHY am I rocking […] Click to continue reading this post →

Congratulations!

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In other interesting announcements today, the great physicist Alexander Polyakov has been given the Fundamental Physics Prize. (See the announcement here.) There was a remarkable award ceremony in Geneva yesterday, hosted by Morgan Freeman, and with lots of Physicists and others celebrating great work in various areas of physics. Polyakov has been a key and brilliant leader in many areas of theoretical physics, and influenced so many ideas and techniques that have fed into the whole field, and so this is a well deserved recognition.

I must note that it is a bit sad (to say the least) to do a google search on the news about this prize and see so many articles with a lot of just plain stupid focussing on a big prize going to a “string theorist”, as though this is somehow negative or ironic, and also missing the fact that Polyakov’s contributions are so broad and far-reaching […] Click to continue reading this post →