In fact, the last several days have felt like this, with regards big decisions about various administrative roles I’ve been asked to consider taking on. It never seems to end, and I am terrible at saying no to as many things as I should. And I have a bad habit of doing things to the best of my ability and hence I get a reputation as the guy to ask to do a task since I did a good job last time, and so it gets me sucked in deeper into the administrative quagmire, and so on and so forth.
Rather like the “entrapment events” that happened in the La Brea Tar Pits so long ago (have a read of what I wrote about those on a field trip to the Page Museum a while back). I was wandering around the LACMA and Tar Pits grounds yesterday evening after a shoot for a show (a fun thing coming that I’ll let you know about shortly) and made a phone call to say, after ten days of Click to continue reading this post
Here’s what almost ruined my morning on Monday. I decided to cycle the Brompton all the way into work, and went a different way as a change of scenery. At some point, my bike chain started making quite the racket, with a jarring action as I pedalled, but there was nothing visible wrong with the chain, and the gears seemed to be working just fine in terms of shifting – but the problem persists in all gears: The chain keeps trying to jump off the rear wheel every few inches, and then pops back on again. I could not see the problem at all, and I had to get into work for a meeting. My working theory was that I’d stretched the chain somehow so that it no longer fits the bike, but none of the tools I had were going to be able to help with that.
Happily, that different way I’d chosen meant that I could struggle on for a bit longer (enough to get me out of traffic, and do a bit of coasting when I could) and then walk the Brompton over from the end of Virgil to the subway stop at Wilshire and Vermont and complete my journey using the Red and Expo lines.
When I got it home, I put the bike on the high stand, and did a bit of investigation with the better visibility, and there it was. Bizarrely, the larger of Click to continue reading this post
I heard this morning that she passed away today. I’m very sad about this, but also so very happy to have heard and read her work, a real lasting and and sustaining gift. I still remember the chills I felt when first hearing her read “Still I rise”. I’m quite sure that you’ll be seeing it reproduced all over the place in the next day or two… And I don’t feel any shame in following suit, so find it below. I’ve also included below an embed of a film of her reciting/performing it many years after its publication. It’s an even sweeter version in some ways. And here is a piece from the New York Times.
So thank you for embodying and encapsulating Hope so wonderfully, Maya Angelou:
Click to continue reading this post
Memorial Day – 26th May 2014. I arrive at downtown Los Angeles to enjoy a few moments of the pure joy of looking. Of seeing something in front of me well enough to make a rough representation of it on a piece of paper in front of me, for the pure hell of it. This is the essence of sketching. It is about seeing. I’m looking for the… something.
My hunt is over. I see the scene I want, just off the Water Court, a few minutes from the top of the (closed) Angel’s Flight rail. The sunlight is streaming through the portal framed by the two closest buildings. The further ones make sharp geometry against the 4:00pm sky. I’m also curious to try some new coloured pens, and I like that each building suggests a different colour. I’ve got about 15 minutes before I have to leave to pick someone up.
I sit. I start. Immediately I see the guard see me from across the way, and within a minute or two he is by my side, standing in front of me. He has the “You’re not allowed to do X” look on his face, but he’s trying to start out well. I’ve had this before, right in this public space, when a guard decided that I should not take photos of the buildings. Despite all the other tourists who do so. He begins:
You know, usually we… Are you an architecture student?
Are you an architecture student?
Well, what are you asking me, really?
Are you an architecture student?
Click to continue reading this post
So it happened again. I got musing to myself about something and decided to do a quick computation to check it out, and it took me down an interesting rabbit hole, which resulted in me writing a nice little paper at the end of last week that appeared today on the arxiv. I think the physics is really really nice. Let me tell you a bit about it. It is in the same area of ideas that I mentioned last time, concerning that paper I wrote last month. So let me pick up the story there, since I did not really touch on the core of the story. [Note: for non-experts, the following will get somewhat technical and full of terms and ideas that I will not explain. Sorry.]
One of the things that might have struck you (if you’re an expert in the area) from my proposal to make heat engines out of black holes that do real mechanical work like the engines you read about in physics textbooks is that there ought to be no actual mechanical work since there’s no pistons – no pistons changing volumes and so forth. That is (or rather, was) a missing ingredient in the standard thermodynamics of black holes in quantum gravity. Well, that all changed a short few years ago with the work of a number of authors, particularly with the clear suggestion of David Kastor, Sourya Ray, and Jennie Traschen, and work by Brian Dolan, with a fair bit of followup investigations by various other authors including some I’ll mention below. (Update: Two reviews, with different foci, can be found in here and here.) The general idea is that if you allow the cosmological constant to be a thermodynamical variable as well (and there is a long history of authors considering this in various contexts), where it naturally acts like a pressure , (G is Newton’s constant, and I’m setting various other constants to unity in the usual way) then you naturally include a conjugate to that variable that should be the pressure.
For a simple static black hole like Schwarzschild, the volume turns out to the the naive volume you get by taking the radius of the black hole and forming Click to continue reading this post
Been a while since I got to do some sketching. It is good practice to try to do something every day, but that fell by the wayside a little as far as proper sketches went. It has been busy the last week and a bit, and my subway time has been during very busy times when there’s not enough space to get out pen and paper and sketch a person without becoming a spectacle… and during the moments where I might have caught something, I’ve actually been calculating – working out questions for the final exam in the General Relativity class, and (more recently) doing some computations for a paper I’ll tell you about shortly.
Anyway, when time is short, I sometimes like doing quick sketches with a thicker pen. Stops me from digging into the details too much. In fact, I’m really liking that as a sketch mode these days… You make your lines boldly and you’re stuck with your choices, and so it gets you thinking about what’s globally important carefully before jumping in.
It is great and satisfyingly distracting fun. Anyway, between this and that over the last day or two I did a few quick faces based on some photos I found in a Click to continue reading this post
….Let’s hope it is not equipped with a low-flow shower head though. If you get a chance this evening, find a wide area of sky away from as many lights as you can (it does not have to be perfectly dark, but the darker the better). There is a new meteor shower, the Camelopardalids…. It is new because the comet debris responsible (we’re flying through debris left over from its tail) has not intersected with our orbit before, but things have been changing a bit (apparently due to Jupiter’s gravitational pull) and as a result we’ll go right through it for the first time (as far as records show). It is expected that there’s a good chance that it will be a high event shower, and it has also been said – I forgot where I read this – that the Click to continue reading this post
The Road goes ever on and on
Down from the door where it began.
Now far ahead the Road has gone,
And I must follow, if I can,
Pursuing it with eager feet,
Until it joins some larger way,
Where many paths and errands meet.
And whither then? I cannot say.
- J.R.R. Tolkien.
Click to continue reading this post
It is Commencement day today at USC! In celebration of that I thought I’d post a picture of my colleague Krzysztof Pilch and I, being a bit silly. We each have one of those excellently practical Brompton bikes (splendidly finished in British racing green, of course) you sometimes have read about here, and Krzysztof suggested that we take a picture or two of us in academic robes riding our bikes. Krzysztof had his academic full gear ready because he was going to go to the hooding of one of his graduating PhD students, but I had no regalia to hand since I was not planning to do anything ceremonial this year. However, I have a master’s gown at home from the old days of being a member of University College at Durham University (I’d have it ready in case I was going to high table dining at the Castle, where that College is), so I brought it in, borrowed a mortar thingamabob (from our colleague Vitaly Kresin, who also took the photos – thanks!), and we were ready for our close up! (I’d forgotten that my gown was designed to go over long-sleeved garments, so it looks a bit odd, but given that temperatures have been passing 100% these last few days, I think it was actually appropriate to be short-sleeved…)
Congratulations to all the graduating students and their families, and good luck for the future!
Well, making it was a bit like a Lego project, and so… fun! Basically, it is ridiculously hot here. The last couple of days have been over 100 degrees Fahrenheit and there are more days of this sort to come. This is not pleasant, in my view. I tend to operate very poorly at such temperatures, and the sun is oppressively hot, feeling like it is hammering on your head, neck, any exposed areas. (We had a wave of this sort a few weeks ago too, which resulted in a new investments in a new shape of hat.)
My main concern however is the various plants in the garden. The planting of Summer crops this year was quite late (largely because the Winter crops were slow to develop due to lack of Winter rain) and so they are still at the delicate stage where a day or two of strong hot sunlight can destroy them completely. No amount of watering can save them from this sun. So I decided to make some shades to reduce the amount of sun on various plants in the garden and on the patio. The idea was to make a nice geometrical shape that allows the plants to be nicely displayed while at the same time protecting them from that mid-morning to mid-afternoon hammering heat that I’ve seen burning the leaves on several plants. I put together a prototype design, and you can see the steps in the photos: Click to continue reading this post
It is Commencement on Friday, here at USC. Thousands of students will be dressing up in gowns and taking part of the ceremonies marking the ending of their time here at USC and the beginning of the rest of their lives. It’s an exciting time.
Merrill Balassone and a team from USC Media Relations came by my office a few weeks ago to take 15-20 minutes of time to do a prototype of a project on this very subject of commencement. The result was fun, and apparently they used it to build onto in order to make the final short video you can see below. They did a great job! It is a group of USC professors and staff** giving brief thoughts to graduating students upon their graduation. You’ll maybe guess what I say in my segment. It is a theme I mention here a lot, as part of my personal war on people being shut out of (or shutting themselves out of) participation in aspects of our society.
The summary of the piece is here and the YouTube video is embedded below: Click to continue reading this post
I think the people at LA Metro were trying to go for all of the visual science tropes in one cliché-filled glance! I’m a big fan of LA Metro, as you know from several posts about it here, so don’t misunderstand my poking fun at their ad I spotted on a bus stop bench. I think it is to do with helpful apps for your phone – presumably they help you use the system more easily, because of…science? More generally, I’d love to believe that people will take the train more because scientists are involved in designing the logistics, but there’s so much evidence against this on both counts, like having the Blue line and the Expo line – that share the same main platform – both boast BLUE as their colours. But put that all aside for now, and let’s simply count off all the sure-fire imagery that will Click to continue reading this post
…Yeah. Somehow sending proposals and samples of manuscripts around by email does not really feel super-exciting to me. But it is the way things are done now, it seems. But this afternoon, I found myself doing something very old-school, which I rather enjoyed, perhaps because it connected me with writers through the ages: Printing up some special packages (proposal, samples, etc, of the book project), putting them into envelopes and schlepping them down to the post office, getting in line, and Click to continue reading this post
Well, it is that time of year. The Jacarandas peaking is one of the many LA markers of the seasons for me. It means that classes will soon be over (in fact they are now) and I’ll be saying goodbye to a group of students, either because a class is over, or because students I’ve taught in earlier classes are graduating and leaving USC. Either way, it is always a time of mixed feelings, and a sense of being in transition in a number of ways. The Spring is already beginning to feel like it is rolling into Summer, and I’m clearing my desk of one set of things and making way for other things.
(Oh, and of course, the other thing that happens this year is that I seem to end up doing a post like this at around this time, right down to within a few days. It usually involves a picture of a Jacaranda tree. See here and look at the list of related posts below.)
I had an extraordinarily good group of students in my Spring class this year. As you may recall it was an undergraduate General Relativity class (see earlier posts on this by searching on that topic). We ended up having a lot of fun with the topic itself, and things were extra good because the students were very Click to continue reading this post
I learned* that over on the Huffington Post, Christian Ott (Caltech) wrote a piece describing research on modelling stellar explosions using supercomputers. When a star goes supernova, what exactly happens? Capturing the physics that goes on is a very difficult problem to do, and in the article he explains some of the difficulties, and some of the recent progress.
There’s a slide show showing some of the results of simulations that have been done of the fully three-dimensional problem, and a little movie that puts it all together.
*Thanks Crystal D.!
This diagram is the cycle for another heat engine (using a black hole as the working substance) that I studied in the recent paper. It is a path made of two constant pressure legs (isobars) and two constant volume legs (isochores) that happen (due to the properties of static black holes) to also be adiabats. See the post.
It got included in the paper as another example where one could compactly write down something useful about the efficiency, since, as it turns out, you can write closed form expressions Click to continue reading this post
As a contrast to yesterday’s quick caricature effort, I went back to one of the pictures in the magazine and did a more careful pencil sketch. Very different kind of exercise and technique needed to coax out the things I wanted to bring forward. It is a scan of pencils, so beware that it is not as representative of what’s on the page in some ways. To add to that I really should do a lot more finish work on this one (rendering of shadows on Click to continue reading this post
This is a good one from the Onion. (I’ve not looked in on them for a while, so this was a funny thing to return to see…*) The title says it all: “Top Theoretical Physicists, R&B Singers Meet To Debate Meaning Of Forever”. Extract:
[...] at the four-day symposium, where they grappled with extant questions regarding the concept of forever that remained unresolved, such as whether forever is better conceived as an infinite, four-dimensional expanse of space-time or, rather, what one second feels like when you’re away from your girl.
“For many years, the R&B community has posited the classic notion that forever is presumed to go on and on like our love,” said Edward Witten, a string theorist at the Institute for Advanced Study, who acknowledged that while time appears to extend unendingly, it is paradoxically composed of discrete moments such as a tender embrace or a single perfect kiss. “This assertion then raises a problem of even greater [...]
Lovely bit of sitting in the sun for a short while after breakfast this morning relaxing by doing some quick freehand sketches from pictures in a magazine. I was experimenting with a pen I love but don’t use much at all – One of those nice inky brush pens by Pentel. Gives some interesting lines that take some getting used to since it is quite a different mark-making tool than the pens I Click to continue reading this post
On Monday 28th April at 8 PM Eastern time (5 PM Pacific) I’ll take part in a live radio interview that you might want to listen to, on a show called Alpha Centauri and Beyond. I guess I’m in the “Beyond” bit? I don’t really know anything about the show except that they like to bring people on to discuss ideas, and when I get a call to come and help sprinkle a bit of science, you know I’m likely to say yes if I can spare the time.
You can see a link to the details here, and you can listen online. As you can see it is advertised as being about me explaining string theory. Well of course that billing is nothing to do with me – I can’t hope to explain any complicated subject like that in the time available – but if asked I will do my best to try and motivate some of the ideas behind the subject. I hope it will be a fun interview and that we will explore a number of interesting topics, and not just talk all the time about string theory, since that could be rather dull, and definitely a missed opportunity… There is so much more to talk about!
Tune in and listen to find out!
See you then.
Yes, you heard me right. Holographic Heat Engines. I was thinking recently about black holes in universes with a cosmological constant and their thermodynamics. I had an idea, it led to another, then another, then some calculations, and then a couple of days of writing, calculating, and thinking… then a day to cool off and think about other things. Then I came back to it, decided it was still exciting as an idea and so tidied it all up as a paper, made some diagrams, tidied some more, and voila! A paper submitted to the arXiv.
I’m sort of pleased with all of it since it allowed me to combine a subject I think is really fun (although often so bleakly dull when presented at undergraduate level) – heat engines – with contemporary research ideas in quantum gravity and high energy physics. So I get to draw some of the cycles in the p-V plane (graph of pressure vs volume) representing the inner workings of engines of particular designs (just like you might have seen long ago in a physics class yourself) and compute their efficiency for doing mechanical work in exchange for some heat you supply. It is fundamental that you can’t do that with 100% efficiency otherwise you’d violate the second law of thermodynamics – that’s why all engines have to have some exhaust in the form of heat, giving an efficiency represented by a quantity that is less than one, where one is 100% efficient. The diagram on the left illustrates the key pieces all engines must have, no matter what working substance you’re using. The details of the design of the engine are what kind of cycle you taking it through and what the properties (“equation of state”) your working substance has. In the case of a car, for example, the working substance is cleverly mixed up with the source of heat – the air/gasoline mix forms a “working substance” that gets expanded and compressed in various ways (in the green bit of the diagram), but the fact that it also burns releasing heat means it is also the source of the heat that comes into the engine (the flow from the red bit) to be (in part) turned to work, and the remainder flowing out to the blue (exhaust). Very clever.
The cool thing here is that I’m using black holes as the working substance for Click to continue reading this post
Did you catch the eclipse last Monday? It was wonderful. Here’s a little snap I took of the progress (taken with an iPad camera precariously through the lens of a telescope, pointing out of a bedroom window, so not the best arrangement). One of the striking things about looking at the progress of it is just how extra three-dimensional the moon seems as the earth’s shadow slowly covers it. It really makes one’s whole mind and body latch on to the three dimensional reality of the sky – you really feel it, as opposed to just knowing it in your head. That’s sort of hard to explain – and you’re not going to see it in any photo anyone can show – so I imagine you are not really sure what I’m getting at if Click to continue reading this post
Eventually, although a bit over-priced in the Hollywood farmer’s market, I do fall for these at least once in the season. As someone whose job and pastimes involve seeing patterns everywhere, how can I not love the romanesco? It’s a fractal! There are structures that repeat themselves on different scales again and again, which is the root of the term “self-similar”. Fractals are wonderful structures in mathematics (that have self-similarity) that I urge you to find out more about if you don’t already know (just google and follow your nose). And Click to continue reading this post
Spotted in the hills while out walking. Three chairs left out to be taken, making for an enigmatic gathering at the end of a warm Los Angeles Spring day…
I love this city.
There is a total eclipse of the moon tonight! It is also at not too inconvenient a time (relatively speaking) if you’re on the West Coast. The eclipse begins at 10:58pm (Pacific) and gets to totality by 12:46am. This is good timing for me since I’d been meaning to set up the telescope and look at the moon recently anyway, and a full moon can be rather bright. Now there’ll be a natural filter in the way, indirectly – the earth!
There’s a special event up at the Griffith Observatory if you are interested in making a party out of it. It starts at 7:00pm and you can see more about the Click to continue reading this post
As you know I am a big fan of sketching, and tire easily of the remark people make that they “can’t draw” – an almost meaningless thing society trains most people to think and say, with the result that they miss out on a most wonderful part of life. Sketching is a wonderful way of slowing down and really looking at the world around you and recording your impressions. If you can write you certainly can draw. It is a learned skill, and the most important part of it is learning to look*. But anyway, I was pleased to see this nice way of getting people of all ages involved in sketching for fun at the book festival! So I reached in and grabbed a photo for you.
Click to continue reading this post
It is nice to see the variety of authors at a book fair event like this one, and it’s great to see people’s enthusiasm about meeting people who’ve written works they’ve spent a lot of time with. The long lines for signings are remarkable! As you might guess, I’m very much a supporter of the unsung authors doing good work in their own small way, not anywhere near the spotlight. An interesting booth caught my notice as I was wandering… The word “science” caught my eye. Seems that a mother and daughter team wrote a science book to engage children to become involved in science… Hurrah! So Jalen Langie (the daughter, amusingly wearing a lab coat) gets to be Click to continue reading this post
I looked for D-Branes, by Clifford V. Johnson… But somehow must have missed it…
I’m sitting on the bus, on my way to the LA Times Festival of Books. I’ve opened my notebook to maybe sketch a face or two, but then I spot an algebraic error on a page from a few days ago, so I set about correcting it….(you know, either for those historians who will argue about my intentions while poring over these once-lost manuscripts…. Or more likely for me in a few weeks, likely to get confused by my own blunder-in-haste with a kindergarten level variation.)
A bearded fellow had boarded the bus and sat next to me while I was doing this. He eventually glances my way, then away, then he does a double take. I’ve been watching him out of the corner of my eye. He starts to speak to me.
Calc or Trig?
Calc or trig?
What are you studying?
I’m not…studying. It is my research.
Silence from him for a few beats, then:
Charged black holes.
I should say at this point that I get this a lot. No matter who I meet out there in the random world, or what they see me writing, the assumption is always that I am taking a class in high school mathematics. Why is that? People, at least guess for some of the time that I might be at least teaching it, even if you can’t imagine people doing research in this area. The grey hairs in my beard are a guide to your assumptions.
Another gripe: if you see someone writing words, and want to engage them in conversation about it, you don’t assume they are practicing the basic structures… Imagine the analogous exchange: Are you practicing joined-up writing madam, or spelling? Neither, I’m writing poetry.
Anyway, back to the conversation. So, as you recall, I said Charged black Click to continue reading this post
We had a midterm in the undergraduate General Relativity class this week. Midterm II. We’d just come off a batch of lectures on black holes (focussing on Schwarzschild and Kerr), and so it seemed very natural to focus on that as the topic. Schwarzschild is the most basic (vanilla) black hole and Kerr is the case of having rotation for a bit of extra flavour. They are both hugely important in real physics – the former for the basic phenomena and then the latter since most objects out there in the astrophysical realm are actually going to be rotating to some degree (and after gravitational collapse, probably a high degree). So I focussed on those in class.
For the midterm therefore, I got the opportunity to have them discover properties of the (less astrophysically important perhaps) charged black hole – the Reissner-Nordstrøm solution*:
…and do a few computations with it analogous to what they did for the other cases in class and in homework. I hope they had fun (like discovering that for a Click to continue reading this post