Random hints and tips

On Chinese, pinyin and spaced repetition

I've been spending the morning inputting some example sentences into Anki (by far the best flashcard program I've found - freeware, very well supported and, most importantly, built from the ground up on a spaced repetition algorithm). Doing this is always a bit hit and miss but I've found a useful series of steps which may be useful for some people.

For example sentences, you can't go far wrong using Chinesepod. The particular example I've been looking for today are sentences using the word 发生 (fāshēng - to happen). Searching in the glossary on Chinesepod you will find a list of around 20 examples which include this character combination - see here. This is all well and good but the pinyin (pronunciation of the hanzi) can only be found by hovering over the characters which makes it hard to copy the sentences directly into Anki without looking up any tone marks you don't know one by one. Perhaps the action of writing the pinyin may be worthwhile but I find writing tonemarks such a hassle that I'd rather spend the time in other ways (US extended keyboard on Mac: Option key + (a,e,v,`)+o=(ō,ó,ǒ,ò)).

The most efficient way I've discovered for getting pinyin directly is simply by copying the characters from the Chinesepod page and pasting it into the popupchinese adsotrans page and hey presto, instant pinyin. Copy this and paste it along with the hanzi and the meaning into Anki.

Update from the creator of Anki (see comments):

...there should be no need to generate the pinyin in another program. Install basic chinese support or the pinyin toolkit plugin in Anki (file>download), and Anki will insert the pinyin automatically

As an additional note I'd always wondered about the placement of tonemarks in pinyin which nobody had managed to quite explain to me. In fact the rules are simple, if not apparently terribly logical, and can be found here, where it says:

* A and e trump all other vowels and always take the tone mark. There are no Mandarin syllables in Hanyu Pinyin that contain both a and e.
* In the combination ou, o takes the mark.
* In all other cases, the final vowel takes the mark.

See the discussion here on Sinosplice with regards to spaced repetition software where several people, including myself mentioned the potential benefits of using SRS on Chinesepod.

Random addition: see here for a review of Chineseteachers.com on Laowai Chinese. This looks like a potentially very useful resource.

On video lectures and time saving

It's been a long time since I mentioned the use of video lectures, but right now I'm going through a couple of courses online which I've found from itunes university (Berkeley, along with many other institutions now place many video and audio lectures online, making my gym time doubly useful!)

This is a great resource, but one of the particular lecturers I've been watching speaks and writes far too slowly for my liking. I'm watching the video in VLC and can increase the speed to about twice the normal rate while still being able to follow along quite happily. The only problem with this is the chipmunk effect by which on speeding up the voice, the tone is raised. A quick look around gives a solution to this too. If you go into the preferences of VLC and click on all in the bottom right you will get an advanced menu. In this menu, go to Audio:Filters and click the button marked "Audio tempo scaler synched with rate. This will activate a plugin called Scaletempo which brings the tone of the voice back down to the original while allowing fast playback.

These lectures (guide for the lectures here) by John Conway on the free will theorem are a lot of fun.

On Research

I've spent the last four days simplifying a series of equations by hand from around 200 lines of mathematica code down to around 20. Some day I'm going to set up a supervised neural network which will learn how to simplify equations a whole lot better than the current Mathematica algorithms can! Thankfully although this has been a painful few days of tedium the result is that all the numerical instabilities have vanished from my calculations and as I sit here (unless there has been another powercut) my code is churning out meson masses in a model I've been working on for a good few months.

In the next couple of weeks I have to write a talk on our latest paper which has just been accepted for publication, and get a little further through my To Read pile sitting precariously at home. September holds so far a trip to Milos to a conference which looks to be packed with people and talks (eight hours a day!), including my own.

Enough, lots to be getting on with but a couple of photos to finish both taken from my window zoomed in with a 300mm Canon lens.

The wind turbines in the sunset

And the moon with Arcturus:

Importance of a good caffeine intake in research

Perhaps the brand should have been included in the acknowledgments, but this is the most firm evidence I've yet seen for the place a high level of caffeine intake should take in one's research:

The paper in general looks impressive, but page 19 particularly!

NB. This is not a mistake, it's included as a pdf on the background.

(That said, I've been on the wagon for five months now and feeling better for it.)

Rough and tumble

It's a strange profession when a seven hour argument is the highlight of your week, but that's the way it goes in research. At around two this afternoon we started a discussion on a new idea that we've had over the last week and started battling out all aspects of this problem, from the mathematics and the feasibility to the interpretation and possible power of the model. Things got heated at times and we went through all possible combinations of disagreeing with one another, but as we left to go for dinner at around 9pm, we were all very happy, not just with the outcome, but because this is what we love to do. It's a strange game of strategy, knowledge, luck and judgment where each person tries to understand the situation, put their own spin on it and persuade the others that their interpretation is right, but it's an exhilarating one, and this sort of collaboration is my favourite kind. Who knows if this idea will come to anything, but the process so far has been a lot of fun, and we've all learnt a great deal already, by confronting old problems in new lights.

Tomorrow we've agreed to spend some time knuckling down and actually doing some more of the mathematics which underlies our idea, as by the end of our seven hours today, we were running in circles. Anyway, after raised voices and looks of despair, we left with friendships perfectly intact knowing that this is the way research goes.

In fact tomorrow is Korean independence day, but it seems like in the university, all will be as normal. Tomorrow evening I'll be going to a couchsurfing meetup in nearby Hongdae which should be a lot of fun.

Now, to relax a bit I'm trying to catch up on some of the Olympics on one of the 70+ channels on TV, however, here in Korea it seems that almost the only televised events are ones where there are Korean high hopes, which makes for a rather restricted cross-section of the games. Strangely, or not, I found the same thing in Japan and China at various times. I'm not sure if I just haven't watched English TV for too long, but I seem to remember a rather more global outlook on sport, though that may simply be that we wouldn't have enough events to fill the timetable if we only watched games we were good at!

State of flux

Recent developments have radically changed two of the projects I'm working on which means that I'm now feeling in a bit of a state of chaos, in a good way, I think. This means that besides juggling last night in a flood-lit parking lot with the Beijing juggling club from 10pm till midnight last night (our venue was being deconstructed next to us as we played, ready for another shopping mall or similar) and English corner tonight, I've lots to be getting on with.

The talks from Strings 2007 (see previous posts for links) are coming online and they are good quality recordings on the whole.

A few quick photos from Tsinghua gardens from the weekend where I sat and worked on Saturday in the sun, overlooking the lily ponds.



Just a selection from those on my Flickr site.

Linear, or otherwise

I've just presented a blackboard talk to the students on 'The linear confinement problem in AdS/QCD', a topic which I'm particularly interested in studying more myself. I spoke about the papers by Karch et al. 'Linear confinement and AdS/QCD', Csaki and Reece 'Towards a systematic holographic QCD - a braneless approach' and Shifman 'Highly Excited Hadrons in QCD and Beyond', all of which are clear and inspiring for future research.

I've rather given up on the summer school, which was either too elementary or a little too hand wavy, or just too intensive on subjects I have only a passing interest in (4+ hours in one day on CP violation from the B-meson sector is more than I can take). There's talk on several Beyond the standard model conferences in the far West of China and down in Yunnan which would be lovely to go to but they're not quite in my area. I'm keeping an eye out for a good cosmology conference, before the KITPC program which starts in September.

Cosmologists, string theorists and string cosmologists should all come to China for this program!

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After completing most of the preparations for my talk yesterday I headed over to D22, a local bar with an eclectic mix of people, music and events, to watch one of their movies. Having seen clips on TV various times I was keen to see The General from 1927 with Buster Keaton. It's a beautiful film, dated and cliched but Keaton is such an incredible physical actor that everything else apart from his balletic movements and amazing expression are rather overshadowed. Slap-stick, especially of the modern variety doesn't do it for me, but Keaton is so seamless and so expressive that it's a joy to watch.

Looking at still photos of Keaton it's a strange contrast to the expression that come from his movements and if anyone knows a good biography of him I would be intrigued to know why this contradiction is so vast.

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Having met him in person a little while ago, I had Jonathan Tel's 'Freud's Alphabet' shipped to me, courtesy of my sister, from England. This is a fictional account, based on the true story of Freud's last few weeks spent in London with terminal cancer. The book is split into chapters labeled alphabetically with Freudian symbols and the book becomes increasingly dreamlike and non-linear as Freud drifts in and out of his morphine haze. Tel's turn of phrase is playful and powerful in equal measure and as long as you don't require linearity and clarity in your stories this book is an interesting journey into dreams, metaphor and the subconscious. Well worth a read.

This links in to the Mario Vargas Llosa book I read while in Japan on the subject of a Storyteller in a Peruvian tribe, which is equally dreamlike, non-linear and imaginatively written. It's been too long since I read it to give it an in depth review but Llosa's story telling, both from his own narrative style and that conjured up for the storyteller's tales of a magical reality weave into each other naturally and give an eloquent picture of an ancient art.

I'm reading another Steinbeck now and enjoying this one as much as ever...expect a review soon.

Mouse brain simulated on a computer

OK, half a mouse brain, but even so this seems to be an incredibly exciting step.

From the BBC comes the news that the modeling of around 8 million neurons with up to 8000 interconnections each was conducted on the BlueGene L supercomputer and...

The vast complexity of the simulation meant that it was only run for ten seconds at a speed ten times slower than real life - the equivalent of one second in a real mouse brain.

On other smaller simulations the researchers said they had seen "biologically consistent dynamical properties" emerge as nerve impulses flowed through the virtual cortex.

In these other tests the team saw the groups of neurons form spontaneously into groups. They also saw nerves in the simulated synapses firing in a ways similar to the staggered, co-ordinated patterns seen in nature.


I'd love to know from experts how realistic this is and how much further we can go with current technology.

Update: From what I've found on the subject it seems that the link to the mouse brain was simply a comparison of the number of neurons and synapses. The structure, unsurprisingly was not there. The paper is supposed to be linked to here but doesn't seem to be working right now.

Conservation of energy

I have a sudden burst of energy. Usually this is the first sign that I'm about to come down with a bug, but I'm going to ignore that for now and go with the flow. NormallyI would go to the gym, have a big session and completely wear myself out. Luckily the swimming pool I've been going to here is closed now so I'm going to try and use this burst of energy to be productive and get some of the things which I've put off for a while out of the way.

The burst of energy is partly a sudden realisation of the number of things I want to get done in a finite amount of time. The number of places I still want to see in Kyoto in the week I have left. The number of papers I want to read, books I want to finish, calculations I want to do and on, and on, ad infinitum. In fact I'm too tired now for much of the above to be accomplished succesfully, so I shall try and write up some of the less taxing things I wanted to put on the blog.

In fact, I'm sitting on the bus on the commute back to my hotel as I'm now staying the other side of the city. Everyone is giving me strange looks, as I type away, but I'm in the mood that a half our sitting, doing nothing is a wasted half hour. Usually I would be listening to my Chinese practice lessons getting similar strange looks as I mumble the conversations back to myself, but now's not the right moment. (I'm now around 40 lessons through the Pimsleur course and my opinions haven't changed that it's the best resource for beginner's Chinese that I've yet come across - two lessons a day will give you some very basic, but usable Chinese in a month. Without a teacher this is as good as you're likely to get.)

So, four weeks into Japan and the status report is that my work is going OK. I've spent a fun, but tiring couple of weeks working in an operational mode which is very enjoyable. As a theoretical physicist, I often spend a lot of time getting the mathematics of my calculations right. The physical interpretation often fits in at the beginning and end of a calculation (in my experience).

That is, you think of an idea, you work out how to do it, you then spend a long time doing the calculation and getting it to the stage that you believe it to be the 'correct' answer to your original question. The last stage is then working out why you got the result you ended up with. The first and last stages are the stages where I get to call myself a physicist. The middle is usually mathematics and computer programming. They're enjoyable and challening, but it's for the buzz of coming up with the idea and the thrill of understanding the answer that I do what I do.

I'm lucky that the work I've been doing for the last few weeks is a good mix of maths and physics. My collaborators and I have simply been working out what the mathematics that we're playing with means, physically and how we can push it in different directions, without making the physical picture meaningless. That's in some senses the idea of theoretical physics. You come up with an idea which is on the edge of what is known, you then play with the idea and see if it keeps you within the realms of possibility or whether the results are simply impossible. That's clearly a great simplification, but it sums up some aspects of it.

In order to work out whether the ideas we're coming up with are meaningful I've had to do lots of reading of papers in areas which I am not familiar. This is good for me but is also challenging, learning the terminology and methods of reasoning in (what in this case is) a far more phenomenological field than that which I am used to.

Another thing that has got me buzzing this evening is reading a post over at cosmic variance on Boltzmann brains, a topic which I know very little about, though it is something that I've been thinking about from a non-technical standpoint, for a long time. Reading this post, and the far more in depth study written previously here, has motivated me to sit and read some of the papers, though there are so many topics that I want to learn about that I fear this one will simply be added to the ever growing pile. Read the above linked posts for an interesting, if cursory discussion of some of the truly deepest questions in physics, including: why does time seem to go the way we perceive it to. Whether or not you've pondered this before, it's a truly massive question and a fine line to tread between metaphysics and real science.

I have my own thoughts on Boltzmann brain's, but I want to ponder my arguments before baring my soul :-)

Pause - OK, I'm back home in my flat. I went to a cafe that I spent all Sunday working peacefully in to see if I could use my laptop there but they didn't have wireless connection. In fact of the 6 or 7 cafes I've spent time working in here in Kyoto, only 2 have had internet connection. Compare that to Beijing where almost every cafe has internet connection and all expectations are suddenly reversed. This is a pity because the gentle hum of a cafe late at night is one of the most conducive places I find for good work. So, I'm back in my apartment, the terrible Japanese television programs are well and truly turned off, msn is off, skype is off, even the BBC news site is off and I will see what I can achieve now.

The things I want to get done are not all related to my work. I've been reading some great novels so, in the next post or two I will try and give some brief reviews. If you're looking for a synopsis of the storyline in a book, you're unlikely to find it in one of my reviews, that's not the way I work.

Talking of books I've just written a large section about my confusion with the Japanese fascination with Manga, and then deleted it. I can't quite state my thoughts on this clearly. I find it strange that this nation is so engrossed by these comics. I know I appear to use Wikipedia as a default but it often happens that I search around on the web and find that Wikipedia does have the most complete information that's accessible on a subject which I'm not familiar with. Again, on the cultural importance of Manga, there's this interesting paragraph in Wikipedia:

"Though roughly equivalent to the American comic book, manga holds more importance in Japanese culture than comics do in American culture. In economic terms, weekly sales of comics in Japan exceed the entire annual output of the American comic industry. Several major manga magazines which contain about a dozen episodes from different authors sell several million copies each per week. Manga is well respected both as an art form and as a form of popular literature, though it has not reached the acceptance level of historically higher art genres such as film or music. However, approval of Hayao Miyazaki's anime and other works of manga are gradually changing the perception of anime and manga, placing them closer to the status of "higher" arts (Top of box office charts of all-time in Japan is Spirited Away by Hayao Miyazaki, 30.4 billion yen). Like its American counterpart, some manga has been criticized for being violent or sexual. For example, a number of film adaptations of manga such as Ichi the Killer or Old Boy were rated Restricted or Mature in the States. However, there have been no official inquiries or laws trying to limit what can be drawn in manga, except for vague decency laws applying to all published materials, stating that "overly indecent materials should not be sold." This freedom has allowed artists to draw manga for every age group and for about every topic."

In the cafe I've been frequenting in the evenings to work, students spend hours sitting flicking through these comics, sometimes in deep concentration, sometimes casually browsing through the pictures. I find it strange that so many people of all ages engross themselves for hours at a time in what, at a cursory glance, seem to be somewhat facile stories. I'm genuinely interested by this cultural phenomenon and if any manga fans can enlighten me I'm happy to listen.

OK, I'll try and sum up a couple of novels in the next post or two.

The buzz and the daze

It's been a busy week of work followed by a full weekend of sightseeing. Currently it's Sunday night and I'm tired, both from being on my feet for perhaps ten hours this weekend and from sleeping pretty badly for the last few nights. (Having written up details of the last few days the whole post has become a little unwieldy so I'm going to postpone the sightseeing bit for a day or so).

Thursday morning we woke up to an inch of snow, something rather uncommon in Kyoto but it made for a beautiful few hours until, by 11am there wasn't a trace of it left.

So, I'm knackered, but I'm happy with the cause of the lack of sleep. It's related to an aspect of research which I haven't experienced for a little while. My last few projects have been enjoyable, medium concept and relatively high on computation. I've explored some interesting work with my collaborators which has been enlightening and fun. This means that once you've come up with the idea, carrying through the computation has tricky aspects but they can usually be worked through by staring at the screen for long enough or arguing over the meaning of the problem at a white board.

A few days ago a paper came out which sparked off a series of thought processes for me, linked to something I've been thinking about for a while. The ideas are now swimming around in my head, forming solid foundations as others fade and reform in new configurations. I'm afraid I'm not going to go into any details what the idea is but I wanted to talk a little about some of the enjoyable levels of thought process that go on as such an idea is forming.

What follows hasn't happened this way for quite a while, until now. In the hazy line between wake and sleep, as the shackles of normal consciousnes are lifted I find is the optimum time to make conceptual leaps which I couldn't make normally because life and conscious thought are just too noisy. Trying to imagine higher dimensional objects just doesn't work (at least for me) in a fully conscious setting, but somehow the faculty of conceptualising such things is in there, hidden deeply somewhere - or at least the illusion of it is.

As I've been drifting off to sleep over the last few days my thoughts have been swimming with pictures of the problem I'm tackling and the equations which govern it. I'm not trying to say that the ideas I'm coming up with are exceptional. For a start I wouldn't judge such things and on top of that I'm sure bits of what I'm coming up with are way off the mark. I'm also sure however that some of it is right and rather exciting. This is part of the buzz that drives us (or at least me) to do what I do - starting with a problem which looks like a tangle of creeping branches with a speck of light the other side, as you discover the way the branches really fit together in a beautiful pattern which you can slowly decode is a great intellectual rush.

Unfortunately, within an hour or so of this semi-dream-like state I may have solved some problem. The next stage is to go into the office the next day in a fully awake state to carry out the calculations in detail. Unfortunately it's very difficult to switch these thought processes off and the possibilities keep sweeping in and out to make real sleep very difficult.

I spent many weeks of my last year as an undergraduate in this state as I was spending a great deal of time on one particular problem - coding for selection methods for particle event searches in Babar data. This sounds low concept, high drudge work to a theoretical physicist perhaps, but I found that similar intellectual leaps were needed with parts of the computation as can be found in many problems in particle physics.

I would spend the day tackling a conceptual problem with the code and only in the twilight of semi-sleep would my subconscious be heard long enough to tell me what the answer was.

In fact this was a fun problem. It was necessary to take a set of data from a particle accelerator, including many parameters from each collision (number of electrons, missing energy, transverse momenta, total charge, etc.) and put cuts on the data to look for a particular set of events (in this case we were looking for lepton flavour violating tau to mu, gamma).

The basic procedure is to put constraints on the data - bounds on the total missing energy, a cut on the total charge etc. in order to include only certain events. This is done in order to cut out as many unwanted events (background) and keep as much of the particular event we were looking for, as possible.

This was all tested and tuned on 'toy' data, generated by Monte Carlo simulation, such that when the cuts were optimised and the accuracy known, it could be used on the real data in order to give a bound on these lepton flavour violating events. It turned out that there were three useful parameters which were uncorrelated and therefore were valuable to be used as variables to cut the data on (three momentum in centre of mass frame, missing mass squared and missing energy squared as far as I remember - it's been a long time). You could then plot the data, point by point, in this three dimensional space and place a box around it which you hope will include as much of the data you want and exclude as much background as possible.

However, instead of defining a box region with straight sides in parameter space, it seemed better to design a shape which cut the data more efficiently from the background. The question was what shape to choose. In the end it was possible to describe a relatively generic shape with six parameters.

Running through a large range of six free parameters on the data was going to take around 20,000 years if I remember rightly (10^12 iterations) and marks deducted for such late work would jeopardize my degree. A genetic algorithm on the other hand was just the job. The procedure is simple and I've used this on many occasions when I want to optimise something which has a large number of possibilities - it's not perfect for all such problems, but many.

Here's the general idea: Create ten randomly generated shapes with a random set of six numbers (in a sensibly chosen range). Apply this shape as a cut in the three dimensional parameter space and define a way to grade each one - (good data)/(bad data) would be about the simplest, but not necessarily most intelligent. Keep the best shapes, throw away the worst and breed the best shapes in some normalised fashion such that their offspring look something like each of their parents. Add in a little random mutation as well and throw in a few more completely random shapes. Do the same thing again, and again, and again until the system has settled to an ideal shape. This is a pretty general procedure for such problems.

Rather than 20,000 years this took around five hours. It all sounds rather easy now, but the actual design of the genetic algorithm, its tuning and weighting system gave me many sleepless nights floating about in the code and turning the possibilities around in my dazed head. Anyway, it was a fun project and we got some really nice results.

As I say, during these periods where the conscious and subconscious talk freely with each other (I still don't know whether this is pop-psych babble but it certainly feels right) the buzz of hitting on an idea that you absolutely know solves all your problems not only makes up for the zombie days following but is a motivation for what I do.

Sorry, I got a little carried away there, but I'm enjoying the possible prospects for the current ideas coming to fruition. Now comes the hard work of (in this case) coding up the ideas, reading many more papers to solidify some of the formalism and actually getting real results. Maybe it won't work out but I'm enjoying this current state of work very much. I'm sure that the tranquility of Kyoto is helping with this.

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I've written up accounts of this weekend but will post them over the next few days.

On video lecture resources

Spurred on by An American Physics Student in England (who writes much more eloquently on the subject than I will) and Asymptotia's follow up I've been spending a couple of hours each evening back at the guest house winding down with videos of theory seminars from various graduate summer programs - With a Chinese budget, going out on the town is not on the cards, though I've spent a few pleasant evenings in local cafes. Anyway, I thought I'd talk about these video lectures in general and try and add to the original voice and push to make this more widespread.

Learning theoretical physics is hard - it takes time and effort in equally large helpings. There's so much of it that it's easy to be distracted by a million questions and one could spend years following leads from one confusing point to another. It's clearly very complicated though with practice and time the confusion clears and the mass of formulae converge into a meaningful whole. Sometimes books and people explain things in such different ways that it's hard to see that they're talking about the same thing. Often this can be beneficial however because you build a more structured picture of the given subject - physics for cubists perhaps.

Before I say anything about sitting back and watching videos I should stress that the only way you will learn to use the tools of quantum field theory, string theory, advanced areas of mathematics and the like or indeed far simpler topics in maths and physics is not just to read the hundreds of books on the subjects but to do it.

Many people claim that they don't give advice. This is all very humble but those with experience have been through the system and seen what pitfalls lie in wait. I am keen to hear advice from anyone who has been there and done it, however subjective it may be.

Though I'm not that far from being a graduate myself I think that my memories are fresh enough to provide my tuppence worth on the subject.

I think that the following is one of the most important points to stress to first year graduate students: Now is perhaps the only time that you will have the luxury to be able to sit down and go through all the problems in a book. Do it! Do every problem you can get your hands on. Don't just look at the problems and think if you can do them (though of course thinking about problems abstractly is a useful skill) but write out the indices, dot your alphas and make sure your factors of two are right. This will be obvious to most I'm sure but it's so easy to fall into lazy habits of simply reading books in a comfy chair with a cup of coffee. My opinion is that daydreaming is also an integral part of consolidating understanding in these subjects but in general it won't solve the nitty gritty of calculations.

In my first year I tried to take this approach of going through problems but probably not in a very organised way. I had pieces of paper flying all over the place and ideally I should have ended up with neat notebooks full of the correct solutions which I could easily look back on if I need to do a similar problem in the future.

After this, when you start doing research you (or at least I) won't have time to devote to spending several months going through a book. Currently I do spend a lot of time reading papers and books on various subjects but this is often piecemeal and is on top of pursuing research problems. I usually have to devote evenings and weekends to the former and it's frequently interrupted by the latter.

So, do it, speak to people who've been there and find out what books they found useful and go from beginning to end. If it's an appropriate book you will learn how to solve real research problems for yourself. If you don't do the problems and work through the examples then you will probably be able to sit through a seminar on the subject and know what's going on but you wouldn't have been able to get there yourself.

OK, that said lectures are vital because they give the interaction between student and expert. It means you can follow the thought patterns of someone in the trade and you can ask the questions you can't pose to a book, this is pretty obvious. On top of this if the lecturer is good they will take you at an appropriate pace through a subject. As all good books on learning techniques will stress, stimulating different areas of the brain during learning is a good way to memorize things and so using both the auditory as well as visual inputs will surely be beneficial. I wonder if because our brains have evolved since the advent of language if we're better at learning through speech than through the relatively recent addition of the written word.

Still useful but without the benefit of interaction is to watch the lectures on video which is what I've been doing for a couple of hours each evening. I probably haven't learnt how to solve any of my research problems from them but they've taught me new ways to see things and given me motivation to go and look stuff up in books. Institutes are slowly but surely videoing lectures and making them available to the public. I would urge all institutes to do this. It's a waste not to. There are some wonderful lecturers out there and for something that costs so little, so many people could benefit. This is a treasure trove of resources waiting to be utilised.

As an addition I would hope that at some time there can be a real central repository rather than hundreds of sites dotted round the place with small catalogues of lectures. Spires has a search function for videos but they're not all there. Perhaps it would be possible to include a comment or voting section. I'm sure there are hundreds of courses around the world on QFT but if through time people gravitate towards a particular set of lecturers that's even better for newcomers who don't want to search through all the others.

The lectures I've been watching have mostly been of a relatively basic level but I've learnt things from each one and spent a long time following up leads on the web and in the Yukawa Institute library. If nothing else it's a great chance to sit back at leisure and contrast what makes a good and bad lecturer (though almost all of them have been great) and get a few tips.

Most of the lectures from the ASTI summer school are excellent, ranging from true pop-science level to some reasonably technical first year graduate material. Don't be put off by the fact that occasionally the audio and visual get out of synch, this simply adds to the different ways your brain is having to function and makes the learning experience richer ;-). Lectures from Tony Zee on beginner's QFT, Clifford Johnson on strings and branes, Jeff Murugan on solitons (great but the synch is testing), James Gates on supersymmetry, Don Marolf on black holes and Robert de Mello Koch on the fundamentals of group theory are particularly recommended, though there are many that I still haven't seen. (See below for some hints on downloading these).

The lectures from the PITP school aren't quite so clear but there's still a great range of courses (mostly four lectures each) from the basics of string theory by Richard Szabo and the AdS/CFT correspondence by Mark Van Raamsdonk to slightly more technical lectures by Leonard Susskind on de Sitter space (really not very clear visuals at all).

From the Perimeter institute is another fantastic resource though unfortunately I've not found a way to download them (only viewable as far as I can tell in Internet Explorer). The summer school on strings, gravity and cosmology has extensive introductory lectures.

Serkan Cabi has a long list of pages with videos online and I've spent a long time searching through for the most appropriate. Many of them are streaming but if you want to download them there are programs out there that allow you to do this. In particular I've been using a program called Hidownload which is free for something like two months. For the ASTI lectures the link seemed to break easily and I found a program called DAP which allows resumption of downloads meant that I could go away and over a long time the lectures would end up in one piece on my computer.

Anyway, I hope that's of use. In particular if anyone has the knowhow, energy or power to get a real central repository or search engine which enables comments I think it would be very beneficial. Bottom line - don't waste lectures. Make them as freely available as possible.