Search Results for: USC

The 9/11 Flip

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Dijkgraaf Verlinde Verlinde 9 -11 flip figureOk, so here goes. A bit of physics linked to this all so significant date. There’s this term that people in string theory were using a lot in the middle to late 90’s, called the “9/11 flip”. I think maybe the Verlinde brothers, Erik and Herman, possibly in conjunction with Robbert Dijkgraaf, made the term popular but I am not sure about that and I welcome a correction. [Update, since there is some confusion: I’m talking about the term here, not the technique itself, which is older.]

(On right (click for larger) is a snapshot of one of the figures from their influential 1997 “Matrix String Theory” paper. You can see the use the term there, and it is in the paper’s text too, and soon everyone was using it in seminars and other papers to follow.)

The flip became particularly useful when people were discovering the wonders of “M-theory”, which is the catch-all term for whatever is the parent theory of string theory, something we are still trying to formulate. There are a number of narrower uses of the term, however – some more justified than others. For a while, everyone was thinking about the five ten-dimensional supersymmetric string theories (“type IIA”, “type IIB”, “type I”, and two types of “heterotic” theory) which, prior to the middle of 1995 (actually as early as late 1994 or early 1995) all seemed like totally distinct theories, and in the post middle-1995 era (after Witten’s remarkable talk at strings 1995 here at USC: paper here) were recognized to be all part of the same theory. The universe (at least the continually expanding string theory one) changed radically overnight.

m-theory puzzle
(One of my preferred ways of presenting the puzzle that is M-theory, and how the ten dimensional string theories fit in the puzzle. This is a slide from one of my general talks on the subject.)

The 9/11 flip is really simple, although when a setting is complicated enough, it can […] Click to continue reading this post →

That Sort of Time

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Yes, it has been that sort of time. The last several days have been full of far too many things – several of which it would be fun to blog about – but none of which have left me any time for doing the actual blogging part. What sort of things? Well, everything from social gatherings like a couple of parties and salon-type events on the one hand, the usual work-type events on the other (like yesterday’s reception to welcome new USC College faculty – I find those especially important to show up to as a means of re-engaging with a cross section of one’s colleagues, old and new, at the beginning of the year*), and on a third hand (sorry) there’s been a big crunch on the research side of things. The big crunch saw me in my office until about 3:00am after a long night of finishing up two companion papers with three of my students (this included breaking for a walk across campus at about 8:30pm to get some tasty mulitas at the excellent La Taquiza) and submitting them to the arXiv. Sensibly, the students went home by 1:30 or so, leaving me the silly one to tinker some more until the end. It was a really fun couple of projects uncovering some rather rich physics, and I’ll try to tell you about them some time soon.

So anyway, my plan today was to write you a 9/11 post, but not quite about what you […] Click to continue reading this post →

Switching

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Back in LA, and down at the USC campus. Good to be back! Click below for larger view.

campus overhead from google maps Well, it is the first day of the new academic year’s teaching cycle. I’m here in my office at 7:30am (the power of jet-lag) and somehow have to switch my mind back firmly onto teaching and other matters. It’s always tough to do this, since there are always lots of intensely interesting research issues that continue on my mind from the Summer, and I know that some of those will gradually begin to fade (if I am not careful) as my other duties take up so much of my day to day. My first class (part one of the upper level electromagnetism course) is at 10:00am, and I want to plan out the structure for the whole semester, and write a syllabus to hand out and discuss. As well as the first lecture, of course. I’ve not taught this part of the cycle before, and so I’ll have to be writing new lecture notes.

I want to try some new things this year. In particular, I’ve become increasingly concerned […] Click to continue reading this post →

Location, Location, Location

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Some interesting news about the outreach mission. From time to time, Asymptotia posts get picked up by some of the local blogs of note, such as LA Observed, and that’s just great, since many things I talk about here are right at the intersection of local interest and the arts and sciences, especially education (such as talking in a local school), events such as the Categorically Not! ones at Santa Monica Airport, and issues such as the environment, in addition to the pure fun stuff, and the tasty stuff. For example, Kevin Roderick at LA Observed was kind enough to mention the posts about the Griffith Observatory (the new relaunch, and the controversy about the use of actors in the planetarium show), judging at the Science Fair at the California Science Center, as well as the post on the open day at the Jet Propulsion Laboratory, and the post about cycling in the city (perhaps in combination with public transportation, as an alternative to blindly using your car/SUV for most journeys.)

Well, I was pleased to get an email a few days ago telling me that Outside.In have added added Asymptotia to their list of LA neighbourhood blogs, and the posts will be scanned for local references, and then added to a location map of all blogs posts. So what happens is that you can look at a neighbourhood in Outside.In (I tailored the previous link to 90089, the zip that USC is in, for example) and see marks on a map where blog posts have pointed to, or lists of posts that pertain to a particular zip code or neighbourhood. You can then follow those marks back to the blog posts! It’s very cool indeed. This will work for your neighbourhood too, where ever you are (in the USA) – just put in your zip code.

Each blog in the system also has their own page, and the one for Asymptotia is here. You should go to it to experiment with the clickability, but I also took a screen shot (since I can’t see how to live-embed the map), and so this is it earlier:

outside in blogging map

So far it seems a bit inconsistent with picking things up and I don’t know why, – it might […] Click to continue reading this post →

Boot Camp

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Boot CampYesterday afternoon, feeling a bit down in the dumps for a variety of reasons I decided to head for the hills to clear my head. A good hike often helps these things. My other mission was to begin the painful task of breaking in some new boots. The fantastic repair job that I got done on my faithful old boots that died last year (see here for the full report) held up marvelously, and in fact still holds up, but I will admit that they lost a fair bit of flexibility with the new sole, and although they are great for the medium grade sorts of hikes I do in the immediate surroundings, I’m not really sure that they’d be great on the longer ones. I have not taken them up Mount Wilson, for example. The repair extended their life for quite a bit longer, and they will still be useful, but I decided last week that I should start breaking in a new pair to last me (I hope) another 15 years or so. I decided to try to get something as close to the ones I had as before, and so the Asolo TPS 535s were the ones I got (supposedly the natural successors to my Asolo AFX 530s). So I laced them up (already unhappy with the wimpy laces they have as compared to the big rope-like ones on my old boots) and set off from the trailhead in Topanga.

Boot CampMy goal? Eagle Rock. A favourite of mine. There it is in the photo on the right (click for larger). It’s a relatively quick hike, about 3 miles out, along the Musch trail (not the fire road) and a 1000 foot elevation gain, with mostly nobody around since it is insanely hot at 2:30pm and only mad dogs and Englishmen (so the Noel Coward song goes) go out in the midday sun. I’ll leave you to decide which I am (remember, on the internet, nobody knows you’re a dog). So I was able to speed up the mountain to the Rock and stay there for a while, only meeting four other people heading that way the whole time.

You might wonder why it is called Eagle Rock. I did for a long time, as probably have […] Click to continue reading this post →

SciTalks

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I learned from Jonathan Shock and Sara Tompson about SciTalks. In Jonathan’s words (from a comment on another post):

“There’s now a site where people can link to, review and rate scientific videos online. This is a great step as there are so many wonderful lectures online but currently they’re spread all over the web and it’s always hard to tell the quality and level that a lecture is going to be.”

Jonathan has also done posts about online resources in theoretical high energy physics, including a recent one where he discussed SciTalks a bit more.

jennifer goldbeck on the semantic webThis got me thinking a bit about where we are going with all these resources, how useful they are, and -very importantly- how easy it all is to find, and then to search through. (Imagine there are 10 hour long talks broadly on your favourite topic. Assuming there are no accompanying files, how can you search them to find a specific fact that they might mention, without sitting through ten hours worth of material?) Well, ironically, one of the first things that caught my eye on SciTalks was a rather nice talk by Jennifer Golbeck (given at FermiLab last year) entitled “Social Networks, the Semantic Web, and the Future of Online Scientific Collaboration”. She’s quite interesting about this very topic… She describes online collaboration, data sharing, social networks, etc, all in the context of helping us do science (not just physics by the way!). She also illustrates her subject matter -still staying on topic- using examples of data sets from Facebook, Myspace, Friendster, […] Click to continue reading this post →

Strings 2007

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goya strings The main annual conference in my main field of interest starts today. Strings 2007 is in Madrid, and runs all week. The website is here (while there, have a play with the front page image of the Goya painting – quite entertaining). They promise to update the schedule/speakers page with scans of slides, and video, so you’ll be able to keep track of some of the new developments online. There’s no system for doing this live, or asking questions remotely, so if you want to quiz Ed Witten about his new 83-page monster paper on three dimensional gravity that came out yesterday (just in time for the conference!), or feel the buzz of event-anticipation whenever Witten talks about huge new sets of results, you’ll still have to show up in person.

Why am I not there? Well, it would be nice, but there are lots of reasons I’m not going […] Click to continue reading this post →

Yellow Pear Tomatoes

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Tasty yellow pear tomatoes (click for larger):

tasty yellow tomatoes

They have been showing up all of a sudden (it seems) on this plant from last year. I’d read that this is quite a hardy plant and it certainly is, lasting through from last season, through the cold snap, and now coming back more strong than last year. Apparently, it is quite an old variety, going back to at least the 1750s. […] Click to continue reading this post →

TASI@Home

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This year’s month-long Theoretical Advanced Study Institute -TASI- looks especially good, from my point of view, with a great combination of topics and lecturers. As usual, it is held in Boulder, Colorado. It’s all about current ideas and experiments and observations in particle physics and cosmology. Three USC students are there and I’ve heard from them that things have been great so far.

raphael bousso at TASIWell, the great news is that the TASI people are making the lectures available online a fairly short time after their delivery. The link is here. So even though not there, you can schedule some time to take these lecture courses if you like. I glanced for a while at Raphael Bousso’s first lecture in the series “Cosmology and the Landscape”, and it was clear and very well presented. (This is not entirely surprising – Raph is always an excellent lecturer.) […] Click to continue reading this post →

Masterclass, II

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Don’t forget to catch the latest installment of Joe Polchinski’s rather thorough deconstruction of the nonsense, obfuscation, selective memory, and other confusions that constitute the bulk of Lee Smolin’s attack on string theory.

All the points I’ve had the energy to raise have been made here on Asymptotia […] Click to continue reading this post →

A Fair Bit of Fun with Science

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Yesterday was a full day indeed. The main event? The California State Science Fair. The venue? The California Science Center (just across the road from USC). Here’s a picture of it in case you’ve never been:

california science center
(Click for larger view.) California Science Center (with one of my personal emergency escape crafts cleverly disguised somewhere in the picture – all scientists have emergency escape craft, by the way – along with our plans to take over the world, our lab coat, and so forth…)

science fair briefing of judgingThe time? 7:00am. Yes, we start early, as there is a lot to do for the long morning. The judges all gather in the IMAX theatre for a briefing about the ins and outs of the organization this year, the times at which various things will happen, and a reminder about some of the finer points of judging.

At 8:00am we broke up into groups of judges who will judge various sections. Mine was Applied Mechanics and Structures – Senior. Here, we decided on our collective strategy concerning how we’ll go around the various displays, making sure at least five judges (there were ten of us in total) see each project once in the first round of interviews. We’ll compare notes during the break at 11:00am, agree which ones we should all have seen – in order to focus on deciding which ones get which prizes or honourable mentions. I forgot to take a picture of our group of judges sitting around the table chatting. Most of the judges in my group were people from the aerospace industry, I gathered. About three or four people were new to the whole thing, and so some of us explained a bit about the things that we ought to be looking out for in the judging. This also (given the section were were to judge, and given the makeup of the judging panel – many coming from an industry where the place where the science and engineering are quite thoroughly – and necessarily – mixed together) leads to discussion about making sure to distinguish between a great science project and a great engineering project. It’s also good to be aware, when making comparisons, of the vast differences in resources that some entrants have access to. These two things, to my mind, are very important (and we all agreed). A kid (especially one with access to lots of resources, for example) can dazzle an unwary judge with lots of fancy cool equipment and build something that is truly wonderful and admirable, but that does not necessarily mean that they would have done as much science as the next entrant who has done some very careful scientific experimentation with a innovative way of answering a clearly stated question, but in a less spectacular setting – perhaps mostly using more affordable household items.

science fair students
(Click for larger view.) Overview shot of one of the sections, with poster displays.

Well, with that in mind, we all went off to meet the youngsters! See the project listings here. This is the best part, of course… talking with all those enthusiastic young people […] Click to continue reading this post →

Backreacting Asymptotically

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(Random title constructed to reply to Bee’s post called Asymptotic Backreaction.)

You know, I’ve made some great online friends here on this blog. It’s all the result of that community I’m trying to keep going (and expand) here with contributions to the conversation from many of you in the comments, and even sometimes in guest posts. I’ve been lucky enough to meet some of these new friends since everyone likes to pass through Los Angeles sooner or later. In the past six months, four familiar Asymptotia contributors have passed through Los Angeles and I’ve been lucky and delighted to meet them: – Amara (November; on her way to a conference, and she gave us a talk – I’m trying to get her to do a guest post on her “Watering the Earth” topic one day), Candace (January; on her way to a conference here -she did a guest post) by the way, Athena (two weeks ago, on the way to a conference), and this week I finally met Bee (also giving a talk, and on her travels -she’s also done a guest post by the way) who turns out to have just that same excellent eye for observation, and quietly sharp sense of humour, as her blog posts. (She’s the main blogger behind the excellent Backreaction, and she’s done a post there which briefly mentions her visit to Disney Concert Hall with me.)

Anyway, in the photo below is Bee (click for larger), at Grand Central Market (inserted into a photo taken near one you saw earlier. See also this post.):

Sabine Hossenfelder at Grand Central Market

Tameem, a student of mine, has teased me a bit about my showing visitors around, […] Click to continue reading this post →