Around Fifteen

While on a hiding retreat in another town or city, I like to seek out a local group that might be doing a “drop in and draw” session. You show up, pay your money, and there’s a safe environment (in a studio, a back room, upstairs of a pub, etc) for a model and artists to work on the wonderful business of capturing the human form in various media. I’m a reasonably private person so I like to keep the anonymity level reasonably high, but it does not only work. People are of course on the watch out to protect the group from perceived problems, so they ask questions. Others are just trying to make friends, and so they ask questions too. I just like to be polite and friendly, share the odd joke or remark, but mostly keep my mouth shut and listen to the various small talk that breaks out during breaks. Most of all, I want to get on with the business of drawing.

sketches_17th_march_2014_smallI went to one on Monday. This time around it was sort of amusing to me at one point when one of the organisers of the group asked me why I’d come down from LA to their small seaside town drawing group and I said I was hiding. I could sense alarm immediately (I can imagine the pictures he might have had in his mind even before I said “hiding”) and so I then went further, by way of reassurance, and said something vague but standard about wanting to get out […] Click to continue reading this post

Discovery Clarification

[Update: Over the months following the announcement, doubt was cast over exactly what BICEP2 saw, and now it seems that the signal announced by BICEP2 is consistent with polarisation produced by galactic dust. See here.]

I’m actually in hiding and silence for a week. It is Spring Break and I have locked myself away in a seaside town to do some writing, as I did last year. But I must break my silence for a little while. Why? Well there’s been a really great announcement in physics today and while being very happy that it is getting a lot of press attention – and it should since the result is very important and exciting – I’ve been stunned by how confusingly it has been reported in several news reports. So I thought I’d say a few things that might help.

But first, let me acknowledge that there’s a ton of coverage out there and so I don’t need to point to any press articles. I will just point to the press release of the BICEP2 collaboration (yes, that’s what they’re called) here, and urge you once you’ve read that to follow the link within to the wealth of data (images, text, graphs, diagrams) that they provide. It’s fantastically comprehensive, so knock yourself out. The paper is here.

I keep hearing reports saying things like “Scientists have proved the Big Bang”. No. The Big Bang, while an exciting and important result for modern cosmology, is very old news. (You can tell since there’s even a TV comedy named after it.) This is not really about the Big Bang. This is about Inflation, the mechanism that made the universe expand rapidly from super-tiny scales to more macroscopic scales in fractions of a second. (I’ll say more about the super-tiny below).

I also hear (slightly more nuanced) reports about this being the first confirmation of Inflation. That’s a point we can argue about, but I’d say that’s not true either. We’ve had other strong clues that Inflation is correct. One of the key things that pops out of inflation is that it flattens out the curvature of universe a lot, and the various observations that have been made about the Cosmic Microwave Background over the years (the CMB is that radiation left over from when the universe was very young (about 380,000 years old – remember the universe is just under 14 million years old!)) have shown us that the universes is remarkably flat. Another previous exciting result in modern cosmology. Today’s result isn’t the first evidence.

So what is today’s exciting news about then? The clue to the correct […] Click to continue reading this post

Wormholes!

“So, you have a choice. We’ve ten minutes of class left. I can either finish early, or…. I can show you that there’s actually a wormhole living in this picture, or can I tell you about Hawking radiation.”

wormhole_sketchThat was the choice I presented the students with after we’d spent some time together exploring the Kruskal-Szekeres extension the the basic black hole solution, in my General Relativity class today. You probably don’t know what all that is, and that’s ok. Suffice to say that you end up with a pretty diagram which looks like two everlasting black holes put together as in a sort of elegant trading card. Or perhaps a neat knot where one black hole is sort of upside down and neatly slots into the other one so that they hug each other into eternity, acting as each others’ past and future. Look it up and see.

Anyway, they went for the wormhole, with a chant “Worm-Hole! Worm-Hole!”. So I constructed the wormhole for them… the Einstein-Rosen bridge, as it is known, ending with the sad news that it is not a real traversable wormhole that […] Click to continue reading this post

Science Films Galore!

Sorry that it has taken me so long to get to posting the results of the USC Science Film Competition. It has been super-hectic. In addition to the usual things I have to do, I had to give a talk about science education to the Society of Physics Students – that went well, I heard – read and examine another PhD. thesis (twice in one week), do battle with two fronts of vermin attacks on my house, and prep a whole lot of other things I won’t trouble you with… Also, oddly, the time change seems to have left me in a state of exhaustion each day.

Enough with the excuses. What are the results, you ask? And is it true the winner was controversial?!

usc_science_film_showcase_2014_1Well, first and foremost we had a fantastic time celebrating the work of all the students in the competition. About 75 or so people turned up, making all my frantic buying of things in Trader Joe’s and so forth all worth while, and there were two screening sessions separated by a coffee and snacks break. Since there were twelve films this year (a 50% increase!) there were six per session (I curated things so that the sessions were about the same length), which worked rather well. A lot of the films used quite a bit of their 10 minute allowed duration, and so given that I pause between films to give each team a chance to take a bow, it was in danger of being a long evening, and for that I apologize to everyone, but I do think that the students should get a fair amount of individual recognition for their hard work.

Anyway, to cut a long story to medium, the standard was quite high this year, with several good films at the top that were hard to choose between, but I think the 15 judges (from academia and the film industry, with scientists and filmmakers and scientists-turned-filmmakers on both sides) got it right.

The first prize winning film has resulted in raised eyebrows from some, including the filmmakers themselves who apparently were sure that their film would be overlooked due to its content. I think that the judges got it exactly right. It is a fine example of exactly what I’m looking for in this competition- a […] Click to continue reading this post

Showcase and Awards Today!

science_film_competition_logo_smallJust a reminder: The USC Science Film Competition Showcase and Awards are tonight (March 7th) at 6:00pm. I’ve been tallying up all the judges’ input and have the results in special envelopes to give out tonight. Very exciting. Come along (event information here), and enjoy celebrating all the students’ hard work. There will be twelve films on display!

-cvj Click to continue reading this post

Cloudy with a chance of Physics

I don’t know. That’s a bit of a desperate title. But in exchange, a rather nice cloud formation, don’t you think?

clouds_3_3_2014_1

This was from the sky over Los Angeles yesterday evening (a shot of the sky in the other direction is to the right – click for larger), and my first thought was “what’s the physics behind these beautiful structures?” There’s enough regularity here to expect there to be a mechanism, but I do not know what it is. Some combination of atmospheric conditions like wind speed, clouds_3_3_2014_2temperature, perhaps some layering of different bodies of air, and so forth, resulted in this and I’d love to know more. What factors set the roughly regular size of the structures, their pretty uniform distance apart, etc? (These are typical physicist’s questions, in case you’re […] Click to continue reading this post

LA Phil Rock Star!

When calling to mind the Los Angeles Philharmonic, everyone’s (and all the posters’) focus is on Gustavo Dudamel, (or, the Dude, as I call him), all unruly hair and visible enthusiasm and so forth, and that’s great. He’s an excellent conductor. However, one of the unsung (as far as I know*) visibly spectacular performers of the LA Philharmonic is the excellent principal viola player whose name I do not know [update: see below*] who puts on the most remarkable physical performance every time I go (and presumably those other times too). Actually, the violist who sits next to her is also remarkable, since she manages without being distracted by her neighbour to maintain a very upright and solid, firmly planted, legs wide stance, in part providing a canvas upon which the viola player I first mentioned can splash bright splashes of movement all over the place! la_phil_sketch_28th_February_2014_smallShe rocks, sways, jerks, and contorts (sometimes even during quiet slow bits)- doing the craziest things with her legs, head, and bow arm, and so much of the time looks like she is about to spectacularly fall off her chair and wipe out at least half the viola section! This is why her colleague right next to her is also remarkable, as she acts as this wonderful un-distractable “straight man” to the physical pyrotechnics helping make them all the more remarkable by contrast. Last night I tried to capture some of the energy of the hyper-energetic viola player in a quick sketch (during […] Click to continue reading this post

Take Part in the Festival!

I’ve just returned from a rather wonderful two rainy days in Santa Barbara celebrating the work of Joe Polchinski. (See my previous post for more about this, including a few reflections.) It was a combination of high school reunion, group hug (with Joe in the center), and serious reflection about physics, now, back then, and to come. Now the great news is that pretty much everything was recorded on video, and so you can take part in it by settling down in front of your computer (or other device – those of you in the further (but pre-singularity) future can just instruct the appropriate plug-in from [Cyberdine systems ] [Tyrell Corporation] Google to stream directly to the vision centres of your brain) and view the various excellent talks and panel discussions here.

I had the honour of chairing (and contributing to) one of the panel discussions reflecting on D-branes (as I promised last post). The title was “D-Branes: Tools of the Revolution” and it went very well thanks to my three excellent panelists (Greg Moore, Andreas Karch and Samir Mathur) and many members of the gathered audience who contributed to the free-form discussion in the 15 minutes at the end. Have a look at that right along side the really interesting and lively discussion that Steve Shenker chaired at the end of the conference (which sadly I had to miss because I had to get back to LA through the rainstorm for another engagement). The idea there was to speculate a bit about the future of physics and thereby “Planning for Joe’s 90th Birthday“.

Enjoy.

-cvj Click to continue reading this post

Festival of Joe

20140226-214941.jpgEarly evening. Cocktail (made with Hendricks gin, muddled tangerine, and basil…). Roast pork on the way. Old haunt.

Where am I? At Roy’s, in Santa Barbara. I’m here for a two day celebration of the work of Joe Polchinski, one of the giants of my field. It all begins tomorrow, and I am taking the opportunity to have a quiet bit of time in an old haunt. I was a postdoc of Joe’s back in the mid 1990s, just when the world of theoretical physics was waking up to the awesome power of D-branes. D-branes are a special type of dynamical extended object in physics, and Joe had discovered their importance for string theory just around that time. Roy’s opened around that time too, if I recall, and a group of us became regulars, helping it along in those early days when it was smaller than it is now. (That small group included my friend and fellow postdoc Andrew Chamblin, who passed away some years ago.)

A D-braneSo I am here to help celebrate Joe’s work on the occasion of his 60th (hard to believe that number, frankly), and it will be good to see all the people who show up, and of course it’ll be excellent to see Joe. Part of my help in the celebrations is to organize and run a panel about D-branes, which will be on at 11:00 tomorrow. I’ll be reflecting a bit on the good old days when D-branes really broke, and turned out to be the key tool of the Revolution that took place in the field. In lectures and writings from that time and long after I used to refer to them as the Heroes of the Revolution, and in honor of that and of Joe I have named this session D-Branes, Tools of the Revolutionary, or something like that. Joe helped bring about the revolution, and his tools were D-branes, you see.

I was lucky to be here as a postdoc at that time, and happily I had the good sense to be quite sure that it was going to be important to quickly spread the […] Click to continue reading this post

Introduce a Girl to Engineering Day

Apparently it was Introduce a Girl to Engineering Day yesterday, so some might say I missed it. But as you know, I think that every day should be Introduce a Girl to Engineering Day, so it is not too late! Have a look a website for it I found (here). What can you do? You don’t have to organise a huge event (although feel free to). It can all start small. Maybe for that next gift, consider (if you don’t already) buying your little girl (or someone else’s) a set of LEGO or an electronics kit (or other hands on building toys) instead of the (fill-in-the-blank-standard-girl-toy) everyone else is getting her. Go ahead and make it a pink kit, if you want, since that’s what society seems to want. Who cares what colour it is? Apart from buying, even just chatting a bit with a child about engineering in our lives, and all the people who can (and do) contribute to it would be a great thing to do.

Here’s a short film from our own Viterbi school of engineering:

[…] Click to continue reading this post

Films!

Good News Everyone!

The deadline for the USC Science Film Competition (now in its third year) passed, over the weekend. The good news is that I now have 12 films in the vault (a 50% increase on the two previous years), waiting for the next stage of the competition. They are on a wide range of topics, in a variety of narrative styles, and I’m super-excited to find a block of time and have a look at them. The next stage is judging, and I’ll be assembling the panel over the next day or two and letting them start looking at them and casting their votes.

So keep an eye out for more news soon. The showcase and awards ceremony is on the 7th of March, and I’ll be opening envelopes and giving away prizes with delight, I’m sure. I’ll also be posting films here on the blog for you to look at, once that date has passed.

-cvj Click to continue reading this post

Mass Matters

I was about to do a little post about where we are in the General Relativity class. We’re about to start studying our first full non-trivial solution of Einstein’s equations. Then I had this feeling I’d done it before, so I looked, and indeed the very post I thought I’d do was first posted Feb. 13th 2008. So why not re-post it for your reading pleasure?

_________________________________________________
(First posted 13th Feb. 2008)

Well, only four weeks and change behind us in this course, and… the class (see here and here) is ready to understand this wonderful equation:

the schwarzschild solution

and all that it implies. What is it? It encodes the shape of spacetime around a spherical blob of mass of total mass M. No, don’t worry too much about the details, since this is not a lecture about General Relativity….. it is just nice (I hope) every now and again to get a look at the sorts of things we use in our day to day work. This “warped” spacetime encodes what we interpret as the gravitational field (in the old Newtonian language) due to a spherical (or, to a good approximation, almost spherical) mass. Like the sun, or the earth, or that tennis ball in the corner there*. It is an exact solution […] Click to continue reading this post

No, That’s the Other Guy…

sam_jackson_tvNo, I’m not Neil deGrasse Tyson. Yes, we both talk about science on TV. Yes, we both happen to be black… but no, we are not the same guy. Also: No, I am not Jim Gates. He also sometimes shows up on TV talking about physics, and he is also black.. but no, he isn’t either me (Clifford) or Neil… He’s Jim.

This attempt at humour is inspired (in part) by real conversations I’ve had (less so in recent years, thank goodness – people are maybe better about googling first?). But mostly it is inspired by this (familiar) sad, funny, and stunningly awkward conversation from Monday* (the first 2 minutes 10 seconds): […] Click to continue reading this post

Summing Numbers in a Small World

So here’s a slightly weird thing. So there’s been all this excitement over the web about the old old “shocker” that the sum of the positive integers is -1/12. You know, not even an integer, and not even positive. Apparently there have been articles in the New York Times and Slate and goodness knows where else… and I’ve been ignoring it all since I’m tired of what it often leads to: People wilfully using it as a device to manipulate people’s ignorance about subtleties with infinite processes to make the tired point that string theory is somehow wrong since it is based on “funny math”. I called Lawrence Krauss (who should have known better) out about it some years ago when he did that at an event I happened to attend. It’s a bit tedious, not the least because it is actually part of a wonderful field of mathematics that can get misrepresented, and of course because it has nothing to do with string theory.

So I ignored it all. Then some students in my class asked me about it. And I explained why it is interesting and so forth… Then I carried on ignoring it all.

Then a day or two ago a mathematician colleague emailed me to ask what […] Click to continue reading this post

Straight

In class tomorrow I’ll introduce one of my favourite equations:

[tex]
\frac{d^2x^\sigma}{d\tau^2}+\Gamma^\sigma_{\rho\nu}\frac{dx^\rho}{d\tau}\frac{dx^\nu}{d\tau}= 0\ .
[/tex]

… Wait – Where did everyone go?!

Come back! I’m not expecting you to know what it means, I just wanted to talk a bit with it sort of … nearby. If you consider yourself a bit intimidated by mathematics, be assured that it won’t bite. (No more than a piece of sheet music lying nearby will harm someone who has not learned to read music.)

It turns out that it is pretty geometry! In the equation, we’ve the object
[tex]
\Gamma^{\sigma}_{\rho\nu}\equiv\frac12 g^{\sigma\mu}\Biggl(\frac{\partial g_{\mu\nu}}{\partial x^\rho}+\frac{\partial g_{\mu\rho}}{\partial x^\nu}-\frac{\partial g_{\rho\nu}}{\partial x^\mu}\Biggr)\ ,
[/tex]
called the “Christoffel symbols”. The set of objects [tex]g_{\mu\nu}[/tex] (the “metric”) actually encode the properties of the space you wish to study (like the plane, or the sphere), and the equation at the top tells you what are the “straight lines” in that space. Well, in the plane (like your desktop) they are straight lines, while in other spaces they are the analogue of straight lines – if you want to go from one point to another point somewhere else in the space and desire to travel along the shortest path to do so, you want to follow such a line. It is called a “geodesic”. The equation is commonly called the geodesic equation.

231px-Longitude_(PSF)You know such lines, intuitively, in a non-trivial example. Next time you look at a globe (wait, does anyone but me look at maps and globes any more? I love them!), you’ll probably see examples of those lines drawn in. They are the “great circles”, the lines of longitude, and the equator. (Image used with permission.)

I just made a class worksheet that guides one through a bit of playing with this equation to get the class excited about […] Click to continue reading this post