Have a Fantastic Fourth of July, to everyone who is celebrating it!
It’s been several days since my last confession. Sorry about the silence. I’m honestly not sure exactly what I’ve been doing, since it has been a mostly fragmented set of things, coupled with a generally down mood of introspection over matters personal. Hmm… So nothing new there.
Physics-wise I’m a bit stuck. Not on a particular project this time, but stuck on […] Click to continue reading this post
[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
Well, it was a full day. Since this morning I’ve been putting the last touches on a paper with my student, V. I’ve been working at my home office (something odd going on with my office computer) while he’s elsewhere but present via IM. We can chat, exchange equations, drafts, and so forth, so it is good medium. Then mid-morning, I had a moment of confusion for a while, and progress stopped while I sorted that out. Discussions with V and another student, T, via IM about this and some other matters ensued, and then I was back on track, inputting edits from a session yesterday of reading it with pen-at-the-ready in a bookstore, inputting edits from V, and then another printout and review to add more.
Every now and again, a check of email, a walk around and a pull of the odd weed in the garden, and then back to it. Somehow this went on until 3:00 – three hours […] Click to continue reading this post
Yes, it is that time of year when the city goes purple. Or lavender.
The jacaranda trees go crazy for a while. There are stretches of several blocks long, […] Click to continue reading this post
It has been rather a tiring last several days. I’ve been focusing on writing a big report on various internal matters that my committee was charged to study for the whole academic year. The issues are rather large, and the solutions I was trying to present require not just cosmetic tinkering but major changes in the way things are done. So the key thing to get right in writing it is a tone that is critical of what there currently is in place while at the same time painting a picture of what could be in its stead, while also beginning to show how to get there. If you don’t balance all three just right, there’s no chance that anything will change, since either lots of people will just be pissed off that you trashed their system, or threatened the status quo, or they’ll agree but say there’s nothing that can be done, or they’ll say you have not really thought it through. I think I’ve managed to get the balance right.
It was due on Monday. On Sunday night, I had something down, but I did not really like […] Click to continue reading this post
That’s it. The class is over… I have to admit that I’m pretty sad to see the end of it, although I’m very very tired. It was such a great group. (I’ll be toasting the end of it all with some of the splendid stuff to the right.)
Recall that we stepped away from black holes. After a look at cosmology for some lectures, where we understood the role of four crucial components in determining a universe’s properties (curvature, matter, radiation, and vacuum energy) we dove back into formalism for a short while (one lecture) to develop a little more the tools we needed to properly under stand how to formulate Einstein’s field equations.
It did not take long… You need only the idea that it makes sense to formulate everything in terms of objects that allow you to express the full sense of an equation in any coordinate system you care to write. Once that is done (the objects are called tensors, and the idea and how they work is pretty simple to get to grips with) the key to formulating the field equations of gravity is to have a look at the structure of other familiar systems. The field equations of electromagnetism (Maxwell’s equations) and the field equations for Newton’s formulation of gravity give the required clues. A rummage around the geometry to find the appropriate object to express the physics in terms of uncovers the Riemann tensor and its cousins (“contractions” to get Ricci and so forth), and you’re almost there. A step back to learn how to package energy […] Click to continue reading this post
Wow, doesn’t time fly when you’re having a busy semester! I meant to tell you about this early March shoot a while back, but got swamped and it fell off the desk. I recalled that I’ve been neglectful because I learned that the show in which some of this will be used will air on Tuesday night (9:00pm I think – “The Universe” on the History Channel). The episode discusses the end of the universe, as far as I know. The point is to discuss the various speculations that have been made about how the universe might end, and what current knowledge (such as the famous 1998 supernova observations showing that the universe’s expansion is accelerating) seems to suggest about which of those scenarios might be more likely. Of course, for the discussions to make sense, you need someone to talk about some of the basics, such as what it means for the universe (indeed, the whole of spacetime) to expand and collapse. Who you gonna call? 
Ok. I’m one of many you can call. It was a new (to me) producer/writer, Savas Georgalis, who called this time, and we worked together on plans about how we might […] Click to continue reading this post
Morning cup of tea, and short reflection – coming up for air before diving back in…
It’s a bit of a mess here, time-wise. Just not enough hours in the day. Everything totally fragmented. Yesterday was grueling… here’s some of it:
Up at 5:30am, finding that I’m immediately thinking about a physics project for a bit (I fell asleep doing so, having been the whole evening in the Casbah drinking coffee and doing the same) before having to break off to get ready, get to office early to start an insanely busy day. Answer a ton of email, and deal with other online stuff, planning to ignore it for the whole rest of morning. Note that flimmaker/journalist friend B has sent me an email with a list of comments and suggested changes to my script for the Video. Got to discuss it with A, my collaborator in Chemistry on this. Whenever are we going to meet in the next few days? Sigh. (Must remember to do blog post about this new project, and how I ended up involved with the Chemistry department!)
After some dithering, decided to drive in, since the plan was to stay super-late and probably involve driving someone home.
Cold as I walk to the office from where I parked on the street. Mostly in my mind, and […] Click to continue reading this post
Yesterday here at USC was my last lecture in the class about black holes (see also here). We’ve got to move on to other topics (Cosmology, Einstein’s equations, etc) and so cannot do any more. It was a fun last lecture though. I pulled together a few scraps of things I did not finish in the previous lecture (such as the extraordinarily high percentage of binding energy per unit rest mass you can extract with rotating black hole orbits – just what you need to power things like quasars) and then finished with:
*Of course, all undergraduates commonly hate it when you dare bring in stuff from other classes, so to […] Click to continue reading this post
There’s really nothing like a sweet potato roasted in the heart of a wood fire. A wood fire lit out under a clear big sky with a full moon. After a long day of hiking. A day of hiking in the desert on a super hot day of vivid blue, brown, and gold. Delicious flavours, textures and colours.
I spent most of last week on retreat in Death Valley. It was Spring break, and I was […] Click to continue reading this post
I got an email from one of the group’s graduate students today*, pointing to an archive of videos of lectures by the great Sidney Coleman. He’s doing quantum field theory. This makes this a marvelous resource, in principle, and so I thought I’d share them with you. They are here.
I wonder: are these the lectures that Jacques Distler has mentioned attending a few times in the past on his blog? This was the 1975-1976 year, a graduate course. I wonder if anyone (else) I know was in that class room…
[Update: I learned from the discussion over on Jonathan Shock’s site that there are some partial lecture notes from the course here, by Bryan Gin-ge Chen, based on notes by Brian Hill. He’s looking for help on completing the project, so get in touch if you want to help out..]
I’ve never seen Coleman in action before, and so I was immediately rather curious, […] Click to continue reading this post
The next Categorically Not! is on Sunday March 9th (upcoming). The Categorically Not! series of events that are held at the Santa Monica Art Studios, (with occasional exceptions). It’s a series – started and run by science writer K. C. Cole – of fun and informative conversations deliberately ignoring the traditional boundaries between art, science, humanities, and other subjects. I strongly encourage you to come to them if you’re in the area. Here is the website that describes past ones, and upcoming ones. See also the links at the end of the post for some announcements and descriptions (and even video) of previous events.
The theme this month is Puzzles! Here’s the description from K C Cole:
What isn’t a puzzle? The universe, life and everything are essentially puzzles that, to borrow from Einstein, “beckon like a liberation.” Designing buildings, choreographing dances, cooking meals and getting along with other people all involve solving puzzles (as, of course, does figuring out what’s right in front of your eyes—not to mention putting together a program such as Categorically Not!) A love of puzzles and the challenge of solving them is deeply embedded in human nature.
Gwen Roberts, Scott Kim, Gavin Scott. Our March 9th Categorically Not! features puzzlemaster Scott Kim, who’s […] Click to continue reading this post
