Friday, June 16, 2006

The Middle of the Beginning

I continue unapologetically to take photos of sunsets over the mountains through the skyscrapers from my flat in Beijing. This evening has been particularly sensorally stimulating as I sat on the balcony listening to radio 4 feeling nostalgic, munching on dumplings, calculating solutions to killing spinor equations and looking up from my work occasionally at the stunning view.

With just a day to go (written yesterday) this has been by far the most useful summer school I've yet attended. I realise now how difficult it is to find a series of lectures which is at just the right level to push you without losing you. It's easy to find a school which at first sight is great until you realise that the reason you think it's so marvelous is because you understand it all having covered it before. Clearly not particularly useful.

I spent a wonderful month at TASI last year meeting great people, listening to some great physics and eating superb pizza at silly o'clock in the morning. Unfortunately I have to give a warning about the TASI website and hope that they do something about it for next time (at least the next string TASI). On the website the level of the physics prerequisite is indicated by the comments:

'The audience will be composed primarily of advanced theoretical graduate students. Experimentalists with a strong background in theory are also encouraged to apply. Some post-doctoral fellows will be admitted, but preference will be given to applicants who will not have received their Ph.D. before 2006. The minimum background needed to get full benefit of TASI is a knowledge of quantum field theory (including RGEs) and familiarity with the Standard Model. Some familiarity with SUSY would be helpful'

I warn anybody who reads this to make sure it is true for the year you are going. It was not certainly not true in 2005 and consequently the level was frankly set way higher than I was prepared for. It was perfect for some people but many had sat through a year's worth of string theory grad lectures. Knowing how to quantise a bosonic string and having just about got the hang of homotopy was not enough to jump straight into tachyon condensation, flux compactification and duality cascades. I should reiterate at this point that it's a fantastic school. The month spent meeting people and chatting was worth it but I could have increased my understanding a lot further had I not been sitting in lectures which were way over my head. One year on and now I feel that I could benefit fully from that level of lectures.

It seems strange then that I call myself a string theorist yet I'm currently attending a fairly basic school in the subject and am learning so much (OK, perhaps the new material is only a quarter of the total but the rest is instilling fully in my mind those things which I've vaguely known about for some time). The reason for the gaps in my knowledge are, I believe, because I specialised so early, as most people have to in the UK if they want to finish their PhD in the allotted three years. It's also because I didn't work as hard as some people who miraculously finish in three years and also read all the relevant texts on the subject but I haven't met one of them myself yet.

Anyway, so I've learnt many useful things over the last two weeks. In large part this has been in terms of example calculations which I've never found fully derived in text books. One of these which I've just been running through now is the calculation used to discover how many preserved supersymmetries are in a given supergravity background. The equation itself is simple enough and now having seen some examples illustrated in detail I feel ready to tackle some more complicated examples on my own.

Today we've finished off with a great set of talks on the AdS/CFT correspondence. I'm pleased to say that only a fraction of the examples were new to me but it has got me thinking in some new directions for possible projects.


I thought that perhaps I would be able to have a single lie-in to catch up on sleep before Strings starts for real. An early phone call this morning eliminated any possibility of that. Tomorrow we have a discussion with David Gross in the morning followed by a banquet lunch and then a reception for the beginning of the Strings meeting. I expect to be running on adrenalin only for the next week. I'll attempt to keep as up to date as possible with the various talks at Strings which I feel I can be in the least bit illuminating on.

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