Category Archives: science

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 →

Small Short Film

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A creative team at IBM made a rather elaborate little stop motion film recently*. “Little” is a key word here. The moveable elements are atoms (well, actually CO molecules), moved with a scanning tunnelling microscope! They are calling the project “Atomic Shorts”, it seems. (Pause…) Yep, on reflection, I think I will stay away from all the obvious juvenile jokes that spring to my mind…

See the film here:

There’s a “making of” film (of course), which you can find below, along with some […] 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 →

Bad Luck for Kepler

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Steinn has a nice post about the sudden ending of the Kepler mission, due to a crucial component failure. As he notes:

“Kepler has discovered almost 3,000 planetary candidates, of which about 100 have been confirmed through a variety of techniques, and, statistically, most of the rest are likely to be real planets.

Kepler has not quite found earth like planets in the habitable zone, yet.
It is heartbreakingly close to doing so.”

Sad to see, especially at a time when science is being hurt so badly by continued […] Click to continue reading this post →

Final

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Well, I’ve got to say goodbye to another excellent group of students from my undergraduate electromagnetism class. We had the final today (starting at 8:00am – ack!), and given the lack of rioting, tears, and throwing of rotten fruit during the exam itself, I assume that it was not too bad an exam to sit. Of course, the real measure of what they thought will be how they did in the actual answering of questions, and I’ve not looked to see how that has turned out yet.

Again, I feel a bit sad since it was a good group of students and it was fun to teach them this material. While it is certainly good to move on to other things (I’ve too many projects I want to work on, as usual), I will miss the twice weekly classes with them. Highlights this year include (in no particular order):

(1) The thing I love to do when we are studying dipole radiation – taking the class outside (surprising them somewhat) to look up at the blue sky and connect why it is blue to the computation we just did, including understanding the pattern of the blueness […] 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 →

How is that Supposed to Work, Exactly?

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page_sample_good_roughsWell, yes, I’ve been a bit busy and so posting has been slow over the last week. But I am still alive, and here I am with a sample of one of the several things I was doing. It is some work on the graphic book project. (You’ll be happy that I am sparing you details of tedious committees, faculty meetings, confusing snippets of physics, incomplete musings and computations, etc…)

As mentioned recently, I’ve been doing thumbnails and rough page layouts on one of the stories, and that has been useful for editing and rewriting. I went further and improved an earlier story that I’d written that had mostly been drawn already, and so that encouraged me to do slightly tighter page layouts so as to fit them more closely to the story as it was already drawn, for a smoother final read. I’ll need to find […] Click to continue reading this post →

Lecture Thoughts

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waveguide_plot._cropWaveguides are fun. I mean on the page, although I imagine that they are fun to play with as fully realized physical objects too. But I was talking about them in the context of teaching undergraduate electromagnetism, as I am doing on my class this semester. I tell the class after the second week of class or so that we’re essentially done, and can all head to the beach since by then we’ve completed the derivation of Maxwell’s equations, which describe fully all electromagnetic phenomena. The rest of the class is essentially a semester of picking various situations in which we deploy the equations and study particular solutions. Of course, they realize that there is reason to stay, since that’s really the heart of it – studying those various situations and appreciating the range of delights those equations can yield. Among the most fascinating and delightful of those, er, delights, is light. Electromagnetic waves in general, and we study them in a whole lot of situations, including nipping along unfettered in free space, in conducting materials […] 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 →

Known Unknowns Decreased a Bit

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Well, the day is here. The Planck collaboration has announced a huge amount of results for the consumption of the scientific community and the media today. The Planck satellite looks with unprecedented precision at the very earliest radiation (“cosmic microwave background radiation”, CMB) from the universe when it was very young (a wee, cute 380,000 years old) and helps us deduce many things about what the universe was like then, and what it is like now. Here’s one of the representations of the universe using the new sky mapping Planck did (image courtesy ESA/Planck):

There’s a ton of data, and a raft of papers with analysis and conclusions. And there’s a very nice press release. I recommend looking at it. It is here, and the papers are here. The title of the press release is “Planck reveals an almost perfect Universe”, and some of the excitement is in the “almost” part. A number of anomalies that were hinted at by the previous explorer of the CMB, WMAP, seem to have been confirmed by Planck, and so there are some important things to be understood in order to figure out the origin of the anomalies (if they ultimately turn out to be real physics and not data artefacts). [Update: Andrew Jaffe has two nice posts I recommend. One on the science, and the other on the PR. Jester also has a nice post on the science from a particle physicist’s perspective.]

What is the title of my post referring to? Well, the refined measurements have allowed us to update some of the vital statistics of the universe. First, it is a bit older than previous measurements have indicated. The age is now measured as 13.82 billion years. (I’m already updating pages in the draft of my book…) Second, the proportion of ingredients […] Click to continue reading this post →