[Note: Originally posted on CV on 4th November 2005. 25 comments on it here. Feel free to add new ones here.] ___________________________________________________________________________________ [Warning! This is an unusually technical post.] Ok, so last time, I told you a bit about the motivations for what I’ve been up to. Now I want … Click to continue reading this post
[Note: Originally posted on CV on 31st October 2005. 31 comments on it here. Feel free to add new ones here.] ___________________________________________________________________________________ Well, I suddenly have 45 extra minutes on my hands as I was supposed to be at a very interesting two hour lunch meeting which I’ve now missed. … Click to continue reading this post
[Note: Originally posted on CV on 3rd October 2005. 65 comments on it here. Feel free to add new ones here.] ___________________________________________________________________________________ Below is a snapshot of a computation I was working on earlier this Summer. Will explain later. Spoke about it at the Southern California Strings Seminar. I’m curious … Click to continue reading this post
The next three posts are repeats of posts I did on CV in 2005. They were the first three in the series entitled “News From The Front”, and their subject matter partly lay the groundwork for a post on some new results that I hope to write soon. Enjoy! -cvj
Ok, so which one of you is responsible for this? (Since I started writing the post, I’ve since learned the answer – see below.)
I was watching the 1999 Mars University episode of Futurama some nights back. It’s the one where Professor Farnsworth teaches (among the many excellent lines: “I can’t teach, I’m a professor…”) a course entitled “The Mathematics of Quantum Neutrino […] Click to continue reading this post
A reader asked for more string. You can see my reply here. Not being one to deny the punters entirely, 
I’ll pass on some clips from a 70s British TV comedy show, about string. It was a popular show called “The Goodies”. Some of you might remember them. Well, they did an entire episode with the title “It might as well be string”, and although the clips (below) are out of context and even with not knowing the characters and so forth (I don’t) there are some amusing bits here and there, if you turn it around to poke harmless fun at those of us who work on string theory decades later – It’s all about a PR/Advertising campaign for string!
There’s the string song, the “documentary” about string (best to gloss over the oh-so-funny “smelly Arab” remarks and accompanying laughter), the excellent samples from the […] Click to continue reading this post
Well, I’ve been quiet here because I got rather swamped with lots of things over the last few days. The biggest thing was yesterday. I gave a colloquium at Caltech entitled “Cooking with Quarks and Gluons: Recipes from the String Theory Kitchen”. The abstract is given below. It is mostly based on what I wrote about last Summer.
With all the other things I had to do (including writing and giving two fun two hour lectures on cosmology in my undergraduate GR class) I still decided that it was time to totally rethink how I tell this exciting physics story, and how I present it. This meant designing and building many new slides. Each slide can take a long time to prepare, so this took two solid days of hiding away while designing and building them, only breaking for the other stuff.
Well, it was fun in the end, and today I am exhausted. I decided that you should not miss out entirely on the treats, so I made a little movie of the first parts of the talk to […] Click to continue reading this post
The next regional string meeting is a two-day one at Caltech, this Friday and Saturday, organized by Joseph Marsano. It’s going to be full of interesting talks and conversations, as usual. Please encourage your graduate students to come, especially, since special effort is made to make sure that each talk begins with a pedagogical portion to help non-experts in that subfield navigate and see the motivation.
The speakers are: […] Click to continue reading this post
We’ve been studying rotating black holes in my class this week, which has been fun. We get to apply the techniques we’ve been honing in the context of the Schwarzschild solution (link to recent posts below) to a bit more complicated solution, the Kerr solution, which includes rotation. Some equations follow, although you needn’t be put off by them. Most of this will make sense without really understanding them much. Just so you can see the shape of the things we scribble, I’ll show you the equation that captures this curved spacetime geometry, with no real explanation (sorry):
Here [tex]\Delta\equiv r^2-2Mr+a^2[/tex] and [tex]\rho^2\equiv r^2+a^2\cos^2\theta\ .[/tex] The parameter [tex]a[/tex] is the ratio of the solution’s spin or angular momentum [tex]J[/tex] to its total mass [tex]M[/tex], measured in appropriate units. It’s a very important solution to get to grips with, since it’s not just fantasy physics, but highly relevant for astrophysics since black holes that are “out there” are unlikely to be non-rotating, and in fact, one can expect them to be rotating at quite a clip in many cases. A good many black holes – including some of the […] Click to continue reading this post
Not long ago David Morrison (UCSB) came to the mathematics department here at USC to give a colloquium.
This was a treat for me for many reasons. Here are three:
I’m pleased to introduce a guest blogger today. It’s Nick Halmagyi, who you might have seen comment here from time to time. Nick is a postdoctoral researcher in Theoretical Physics, currently at the Enrico Fermi Institute in Chicago. Before that, he was a graduate student in our High Energy Physics group at USC, which is where I met him. Nick wrote his reflections below for Seed, and he reproduces a version of it (with permission – see details below*) here. I hope you enjoy it.
-cvj
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Theoretical physics is a tough subject. Just one example of how hard things can get is when you ramp up the energy density of a system, the physics used to describe the system itself starts to change. At first it may be a small tweak in the parameters that appear in the equations (the electric charge for example), but then there can be large, abrupt transitions.
The biggest system we study is the universe, and immediately after the big bang all of its energy occupied a tiny region of space. Back then, the energy density was enormous, and as the universe grew over time it underwent several transitions before it became what we now observe.
I’m a theoretical physicist, in part, because I relish the challenge of studying the entire […] Click to continue reading this post
The next regional string meeting is a one-day one at UCLA, organized by Michael Gutperle and Per Kraus. It’s going to be full of interesting talks and conversations, as usual. Please encourage your graduate students to come, especially, since special effort is made to make sure that each talk begins with a pedagogical portion to help non-experts in that subfield navigate and see the motivation. (Photo: Michael Gutperle talking at the first SCSS at USC, Sept. 2005; click for larger view.)
The speakers are: […] Click to continue reading this post
Yep. All done. Sitting in great cafe with a cup of camomile, listening to one of my favourite Mingus albums on the cafe’s overhead speakers, feeling that it all went well. (The latter – Mingus in a great cafe late at night? – is not really the Kentucky I remember.) I seem to have gone three for three. Class, seminar, colloquium. No disasters, besides skimping on the sleep a bit here and there and writing some of the material at the last minute. Good.
So I gave the seminar at noon, talking about much the same material I did in my Santa Barbara talk I mentioned before here. We then went to lunch at a Korean place nearby that was rather good. I ordered the bi bim bap (as I often do at Korean places) and to my disappointment, it did not come in the super high temperature near-molten […] Click to continue reading this post
[Post reconstructed after 25.10.07 hack]:
Two 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
Gosh, a thoughtfully-written general level (more or less) article on some of the general outcomes of string theory research! It’s written by Matthew Chalmers, and is in the Sept. ’07 edition of Physics World*. The article can be read online here, and downloadable pdf is here. The graphic on the right came with the article. I don’t fully understand what it is, but the title, like that of the article, is “stringscape”… Look, let’s not over-think this cvj – it’s a pretty decoration.
I’ve done a quick read of it (should re-read more carefully later on – it will no doubt have some emphases with which I disagree somewhat**) and I’d say it is very much worth reading. While not a perfect summary (what is?), compared to a lot that’s been out there, you’ll find it rather more informed, less sensational, (refreshingly unpoisoned by various prejudices, such as the presentations of Smolin and Woit – see numerous earlier discussions in the “More Scenes from the Storm in a Teacup” series of posts, and others), and unafraid to go to some length to unpack the issues somewhat carefully.
Very importantly, it contains numerous quotes from various respected researchers in […] Click to continue reading this post
