Have these always been these way everywhere and I just did not notice before? Or is it just a Venice Beach thing? The cycle icons in the lanes along the beach are wearing little helmets! Good for them:
(Click for larger view.)
Oh, this reminds me. Some time ago, I was sent a link to a “cycle facility of the month” Click to continue reading this post
I accidentally used the term “de-gauss” (or perhaps “degauss”) in conversation the other day, referring to something I had to do for my well-being. I was asked for an explanation. Thought I’d explain what I meant to you too:
One of many effective ways to de-gauss: Get the best gin ever (Hendricks’), a decent tonic water, the very tastiest of lemons (it’s from the tree in the garden), a glass, some ice*…
…and a really comfy chair. Hey, it’s been a long and busy day.
-cvj
P.S. Oh. There’s some other use of the word involving getting rid of trapped built up magnetic fields, etc., etc. You can google that.
(*Yeah, I know it’s not a great snapshot, but you get the idea.)
I love teaching undergraduate electromagnetism. It has such an elegance, logic, and completeness about it. It introduces such a host of powerful techniques and ideas to the student, taking them across the threshold into maturity in their physics studies: Once you’ve done electromagnetism, you don’t usually think about large chunks of Physics in quite the same way ever again.
Today saw me give one of my favourite lectures, in any subject. It’s always a thrill. Summarize all that has gone before in their studies of electromagnetism – Gauss’ Law for the electric field produced by charges, the statement of the absence of magnetic monopoles (the Law with No Name), Faraday’s Law for the electric field produced by changing magnetic fields (induction:- another really fun set of lectures there), and Ampère’s Law for the magnetic fields produced by a current density. Write them all down next to each other and stare at them. Realize that they are not internally consistent, in general, as Maxwell did (he was motivated slightly differently, but in an essentially equivalent way). The culprit is Ampère, and the problem is fixed by Maxwell’s realization of the existence of the displacement current term. Ah… symmetry. Changing electric fields produce magnetic fields. All is well. Do some nice examples to show how it all works in concrete terms.
The resulting beautiful and consistent set of equations sent a shiver down my spine when I first saw and appreciated them as an undergraduate. They still send a shiver down my spine, and I hope your spine shivers too. Maxwell’s equations:
After the shiver, a lovely warm feeling. From here to light, radiation, Relativity, and beyond…
Every time, I especially love giving this lecture. It never gets old.
-cvj
The Solar and Heliospheric Observatory (SOHO), a spacecraft that studies the sun, has been taking rather spectacular photos of comet McNaught. See here, for example. But the recent news that’s been exciting everyone are the comet pictures from the newer twin-spacecraft Solar Terrestrial Relations Observatories (STEREO), such as this one of the comet’s tail (the sharp lines are artifacts due to bright objects in the background):
Click the image for a larger version. They put together a number of images to make a rather impressive movie of the comet, with a great deal of detail in a sort of fly Click to continue reading this post
The BBC1 are calling her the proud “mum and dad”. I’m talking about Flora, who is the parent of five baby Komodo dragons so far. Read the story at the link above. 
You’ll recall my earlier post about her, back when she featured in the “virgin birth” story leading up to the Christmas period. Just to remind you, she is one of the first Komodo dragons known to Click to continue reading this post
I’m watching my email for an invitation to fly suddenly to the Southern Hemisphere. Perhaps the Latin American Summer School (being held in Argentina this year) needs an emergency strings lecturer? I’ll be happy to reprise my lectures from the one I taught at in Mexico city in 2000…
Why do I want to go South with such urgency? This is largely because Comet McNaught continues to put on a wonderful show in the Southern Hemisphere. Amara Graps has kindly put several links for us to look at in the comment stream of my Look Up Down South post. Have a look here, here, here, here, and here. I did, and I found this lovely shot (by Mary Fanner – click for larger) of the comet over the beautiful city of Cape Town, which I miss a lot from the days when I helped run the ASTI science education program in 2004:
There are several more to be found on the various sites Amara linked to, some that Click to continue reading this post
On the comment stream of my Light Cone post, commenter Neil pointed out something you may find amusing. I quote:
At this website, you can generate an RSS feed of your personal light cone (starting from your date of birth), which notifies you when it passes a stellar object. Quite cool!
He’s right.
-cvj
I don’t know why this possibility did not occur to me before. So let me give you a heads up if you do demos in your lectures. In Physics 100 (which I taught last semester) and in Astro 100 especially, we do a lot of demos to demonstrate various physics concepts. I did a post on the Newton’s third law jet propulsion demo some time ago (linked photo right). My colleague Ed Rhodes did this same demo in his Astro 100 class.
He received an email from one of the students in the class recently saying “Congratulations, you’ve been YouTubed…”.
Apparently, one of the students in the class used his or her mobile phone camera to Click to continue reading this post
Want to have a confidential email conversation about a sensitive issue? There’s not really been such a thing so far, really. Better to pick up the phone and talk in person. Or meet at random near that noisy fountain in the park. But wouldn’t it be nice to be able to send an email and not worry about it being forwarded on, saved – or “reply-all”-ed to the entire organization? I just heard a piece on NPR about a company that claims to offer this service. It acts as the place where you can send and pickup these mails. Once they are read, they are gone. Self-destructed. All very Mission Impossible.
The service is called Vaporstream, and you can hear more about it in the NPR story, by going to the NPR site. I can’t give you a link to the clip directly as it does not seem to be on their site anywhere, so perhaps you will just have to listen to the whole program. (All Things Considered- The Monday 22nd Jan show, toward the last half hour or so.)
Interestingly, it seems that there’s only 8 posts tagged with it on Technorati. It’s been a long time since I saw something with so few entries there! I wonder how long that will last?
I wonder if Vaporstream will catch on and we’ll all be using it regularly in a short time. Will it be one of those things, like YouTube and Google, where we’ll all be wondering what life was like before them?
I find myself confused by why this elementary possibility is not a problem: While Click to continue reading this post
It’s always interesting to hear from others about what set them on the path they’re on, no matter what career path that is. I just read Chanda’s guest post on the matter over at Backreaction. Chanda is a theoretical physicist in training, and so from my point of view it is interesting to hear about her choices since I chose the same career myself.
Since I’m also keen that talented women and people of colour can learn that they can choose to do science careers, and hope that it continues to become increasingly likely that they make their way in such careers with the same opportunities as everyone else, it was also interesting -and encouraging- to read her thoughts (since she is in both categories). Have a look at her post yourself, and also her post on Cosmic Variance about some of those issues.
Whether or not you read it, don’t hesitate to share with us your own recollections. What Click to continue reading this post
On Wednesday there’ll be an evening event about Mathematics and Music here at USC. If you are nearby and can make it, consider going along. It’s free! It is part of the Visions and Voices programme I’ve talked about before. The presenter/performer will be Elaine Chew, whose research is at the intersection of engineering and music. Read more about the event here. You can find out more about Professor Chew from her website here.
Enjoy!
-cvj
So imagine that you’re standing at some spot, holding a big round bulb that can shine in all directions. At a particular time, you switch on the bulb and it shines out brightly. Who has a chance to see the light from your bulb? Let’s not worry about things like buildings, cars, etc., getting in the way of the light, but just imagine it can shine free in all directions. You’ll realize that there is a whole ball of light expanding away from the bulb – light going away from you in all directions. (The edge of that ball describes what is called a sphere, a two-sphere to be precise, denoted [tex]S^2[/tex] in the trade.) The sphere expands at the speed of light. You might imagine that eventually every point in space around you would be reached by your expanding sphere (let’s stay local and not worry about the expanding universe and so forth), and you’d be right. But when? When does it get to some particular point that you might care about? As soon as it takes the light the time it takes to get there, of course. It can’t get there any sooner than that.
Let me put it another way. Your sending out the light is a particular “event”. It took Click to continue reading this post
I’ve been meaning to post this for a couple of weeks and forgot. From the New Yorker two weeks ago (I can’t decipher the artist’s name [Update: Lee Lorenz, I think.]):
I’m pleased to see this for lots of reasons. It reminds me that it was in the New Yorker Click to continue reading this post
You can tell it was a bleak MidWinter day at the Hollywood Farmer’s market last week.
People are actually dressed for outdoor weather for a change. They’re wearing Click to continue reading this post
The show on television called “24” has an interesting format. It is sort of meant to be in real time, and so each episode – roughly an hour long, including advertisements – charts what took place in an hour of a particular day. A whole season is one day. A very harrowing day for the characters in the show, particularly agent Jack Bauer. They are part of an counter-terrorist unit (CTU) trying to save the America from various highly complicated terrorist plots. The terrorists are obsessed with Los Angeles, it seems, which is convenient given that the unit is based in Los Angeles. Having watched two or three seasons of the show now, I’ve also come to appreciate the fact that the terrorist plots hand over to more and more complex and dastardly ones as the show goes along through the day. And the “controlling mind” bad guy earlier in the day is hardly ever the worst and most dastardly person our heroes will meet. There’ll be a really really bad guy along later on with an even worse plan than the one before lunchtime, and so forth. Another reason that it’s lucky that they’re obsessed with Los Angeles, since there’s an excellent supply of theatre and television actors here to be cast in various partsa.
What I’ve really been hoping to see is an episode of the show when Jack Bauer is not saving America/LA. Instead, he’s just… chillin’. Imagine it now:
Click to continue reading this post
