A New Shower!

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Camelopardalids_2014-Radiant_HD1….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 →

Commencement Capers…

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bromptons_and_robesIt 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!

-cvj

Shade Emergency!

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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 →

Advice at Graduation

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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. advice_film_stillThey 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 →

Metro Goes for All the Science Tropes

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science_metro_poster 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 →

Old School Writer

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posting_stuff…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 →

That Time of Year

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jacaranda_april_2014Well, 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 →

When Stars Go Bang…

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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.

Enjoy!

-cvj

*Thanks Crystal D.!

Another Engine

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world_engineThis 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 →

Morning Portrait

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morning_portrait_27_04_2014_smallAs 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 →

Debate about Forever…

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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 […]

More here.

-cvj

*Thanks aef!

Morning Caricatures

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morning_caricatures_26_04_2014_smallLovely 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 →

A Monday Interview

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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.

-cvj

News From the Front, XI: Holographic Heat Engines!

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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 heat_enginedo 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 [tex]\eta[/tex] 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 →