Archive for February, 2009

Stereography: It’s in 3D

I went to see Coraline this weekend. It is an animated movie made with stop motion animation (and it is supplemented by usual CGI effects). I like the medium of stop-motion very much, particularly because it is harder to achieve a good result. The most interesting thing about the movie is that it was filmed in 3D, which gives it a much more eerie feeling. The storyline was ok and there were various aspects that were very predictable. There are some elements of it that reminded me of my childhood: I used to be especially afraid of dogs and I met a lot of kids that didn’t fit in well. I also ended up eating more beets than I liked when I was growing up. Now I really love them, so I can understand a few obsessions that are portrayed in the movie. I think the thing I liked the most was that they did not use the 3D to do that usual ‘trick’ of having objects point towards the audience over and over again. There was a  bit of that at the very beginning, but it soon faded away. (For an example of bad – or you could also say tasteless- uses of 3d, see this blog review of Beowulf)

Now, back to the 3D. Just to tell you a  little bit about the technology involved (feel free to go to wikipedia for more info). The basic idea is that we have stereographic vision: we have two eyes, which is really good for measuring distances by angles of triangles. So ideally, each eye sees a slightly different image and our brain reconstructs a 3D map from two 2D-images.


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Back when I started my job at UBC, I remember dropping by our student’s journal club. I was happy to see that the students took initiative and had a very active club, reading and discussing review papers once a week. Good for them, I thought.

I am a great fun of such clubs. Even if your department, like the one at UBC, offers introductory graduate courses in quantum field theory, and string theory, and particle physics,etc., it is still the case that most of what you need to know as a graduate student lies outside your coursework. Along the way you’d be frequently required to pick up new skills and new knowledge, which is precisely why being a theoretical physicist is the best job in the world. Since picking up new knowledge quickly and efficiently is one of the required skills for the job, may as well start early.

Only problem was, the review articles that club was immersed in, how shall I say it gently, were not of central importance to their futures. In fact, I was kind of shocked by the amount of effort going into completely marginal topics (no examples, I realize where we are). So, I started advising this group, and future journal clubs, on what they can benefit from.

In choosing a good review article to discuss in a journal club, or to give to a graduate student, I used several criteria. First, the topic has to be important and long lasting, still relevant for research in say, 5 years. In addition, it obviously has to be well-written, and have a good selection of topics, emphasizing the ones central to the community over the author’s favorite work. Finally, it has to be fun. If you need to know what that means, go read some of Sidney Coleman’s legendary reviews, for examples those collected in his “Aspects of Symmetry”.

These were more or less the same criteria we used in coming up with the curricula for our (ongoing) summer school series “Strings, Gravity and Cosmology”. At some stage, I started collecting those references in one webpage, what every student should know. This is one of those projects I took on and never finished, so the list there is far from being comprehensive, it is a good start but it needs many more additions. Since I now have a blog, I can ask our smart and informed readers, what should I add to the list? please let me know if you can think of topics that should be covered, or specific references that cover them well. If this generates lots of good responses, maybe I’ll try to update my list and post it here sometime.

(Also, one gentle reminder: references to your recent treatise on the theory of everything do not, sadly, count as something central to students’ future. Since I am trying to protect the establishment, I’m likely to be narrow-minded and delete references to any truly revolutionary work).

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This is an important and interesting issue, which perhaps does not get enough love, so I was happy to see this discussion of chiral gauge theories on the lattice. There will be a followup tomorrow (update: here it is), I’d be also happy to hear about lattice supersymmetry, something I was pretty interested in a while back.

Update: For a not so recent reference on the subject, look at Martin Luscher’s lectures. More recent references, if some readers can think of any, would be appreciated.

Another update:  There will be a guest post here on lattice supersymmetry in the near future, stay tuned.

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We now have a few working examples of a microscopic theory of quantum gravity, all come with specific boundary conditions (like any other equation in physics or mathematics), but otherwise full background independence. In particular, all those theories include quantum black holes, and we can ask all kinds of puzzling questions about those fascinating objects. Starting with, what is exactly a black hole?


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I thought it would be good to point out the opinion article by Stephen Quake on the New York Times on how we artificially create barriers between

applied science and pure science.

On another note, please be patient as current time demands have prevented me from having a more regular blogging schedule.

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Writers block

As it is not surprising, even in the medium of a blog one can get writers block. Even though I can comfortably believe that I will be forgiven for any silly thought or misspelled word, I still find myself unable at the moment to find a topic or post that I would be willing to spend some time on writing.

I have plenty of topics that I plan to cover, but I just can seem to find myself in the mood to write anything remotely interesting. The worst part of it all, is that it seems that this is the 100th post of the blog. So, it should have been special. Oh well, what can I do?


Of course, I can deflect by sending you around the web. 


Bee has some interesting thoughts on science journalism.

Terrence Tao is compiling a Latex for WordPress bug collection.

Peter Coles talks about the ecliptic anomalies in the WMAP and he has quite a few pretty pictures to go along with it.

Gordon Watts seems to have the next generation of CV technology in his hands.

Apart from those, we were celebrating Stanley Mandelstam’s birthday at the KITP here on Friday. I could not attend all the talks because I had to teach class, but it was really nice to see how relevant Stanley’s legacy is, even today. From the talks I could attend to, I found the talk by Joe Polchinski to be truly amazing. It was really a pleasure to see it live and I found it to be very inspirational. It is one of the few online talks that I would really recommend for people in the business of string theory and related areas to hear and see.

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Happy Darwin day!

In the name of scientific anniversary celebrations, it seems that today is Darwin Day. Since this year marks the 200th anniversary of his birth, it is somewhat special. To celebrate in the spirit of the  silliness of the occasion, here below you can see how random mutations actually happen.


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There is an interesting article in the New York Times about the current science funding structures that depicts how hard it is to be truly creative and independent given the current model of science funding, especially if you are young and not established yet.

I thought it would be instructive to have a dialogue about this in this space.  So please comment.

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Comment policy

Since I’m quite unhappy with the way the comment thread of my last post unfolded, I thought I’d briefly set some ground rules and ask for further advice. Here are a few things I did not like:

First and foremost: long, long, long comments about someone’s favorite alternative theory of the universe. I’ll adopt zero tolerance policy from now on. I will, reluctantly, accept links to the innovator’s own blog, but anything else will be deleted. One of the ideas of the blog (besides me having fun) is to serve an educational goal, and I will not have this space serve as a source for false information. Yeah, that’s right, censorship.

Similarly, if you write a comment or two which does not catch anyone’s attention, I’d recommend chilling for a little while. I’m tempted to start deleting or shortening long manifestos that lead nowhere. While we are at it, a side comment: my participation in a conversation, or lack thereof, has to do with many things, including my own time constraints. If you don’t get a reply to your question, it is not a reflection on your personality.

Also, other people’s comments, including other string theorists’ comments, do not necessarily reflect my views. They certainly do not always reflect my motivations and approach to the subject matter. I appreciate the help others provide, and I’m happy when they show up and explain their viewpoint in detail. But, in case the conversation develops, it is likely to diverge very quickly from the original intention of the blog post. In this case I’d much rather the conversation changes venue, so it doesn’t clutter the comment thread here.

In the end, despite all the noise, we had a few pleasant conversations, some of which did not yet reach their logical conclusion. For example, I think I still owe Giotis and Amused some answers to their excellent questions. Stay tuned, I’ll get to that.

Any advice or response is appreciated. I’d like this to be a pleasant experience for everyone involved. I have no respect at all for controversy, and I am not trying to generate it, I am still puzzled by the strong emotional response some of these fairly technical issues generate. Similarly, I do not view the comment threads as “debates”, but rather some space for people to share their knowledge and experience, and to learn from one another. Some ground rules do seem necessary to make that happen, let me know what you think.

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Over at Cosmic Variance, they had a recent post on big surprises that one could have in physics. In the comments someone suggested that we should be looking for messages from the creator in the digits of pi. I’m sure this was said in jest, but I’ve seen enough similar attempts forwarded into my e-mail box to know that this goes on.  Of course, this is just one more version of what we in physics pejoratively describe as numerology: some random collection of facts about some really important mystical number, that has no physical mechanism to describe a physical situation . Apart from pi, another very popular set of such numbers are 42 and 137. The plan of this approach is that everything there is to know about the world is encoded in these numbers, if you only have the correct algorithm to decode it. One of the popular algorithms is to look for the digits of pi or some other irrational number and to try to see patterns in them.


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