String Theory, With a View Towards Reality

By Sean Carroll | April 19, 2006 1:25 pm

The Arthur H. Compton Lectures are a great tradition at the Enrico Fermi Institute here at the University of Chicago. Twice each academic year, a postdoc (!) from the EFI gives a series of 8-10 lectures on Saturday mornings, aimed at the general public, on a topic of current scientific interest. The EFI focuses on research in particle physics, astrophysics, and gravitation, so that’s what the lectures tend to cover. They are a great resource, and it’s amazing to see over a hundred people from the community trudge to a lecture hall every Saturday morning to hear about modern physics.

This Spring’s lectures are being given by Nick Halmagyi, a string theorist whose office is right across from mine. The title is String Theory: With a View Towards Reality, and Nick is gradually putting notes and slides online. With two lectures gone by, reality itself has been the focus thus far, as Nick sets up the current state of particle physics. String theory will undoubtedly follow, and when the moment comes to draw the connection between the two time will probably have run out.

Previous Compton lecturers are a distinguished lot, including our very own Risa. The EFI does a terrible job at keeping them online, but I was able to dig up slides from a few recent lecture series.

Any recent ones with online slides that I missed, let me know. And if you’re in the neighborhood, anyone is welcome to come to Nick’s lectures, which are at 11 a.m. most Saturdays. He speaks with a distinct Australian accent, but it’s ususally possible to understand him.

  • Cynthia

    It is rather unfortunate that these Compton Lecture Series are not webcasted for all of us to enjoy. For those of us incapable of jetting to Chicago to view every interesting lecture, webcasting provides a practical alternative. For instance, I can easily access a number of outstanding lectures archived by Fermilab Media Services. More specifically, for example, Scott Dobelson recently presented three excellent/back-to-back lectures on cosmology. His talks are geared towards telling a story about the evolution of the universe. Perhaps – in the near future – you can convince Caltech to up-grade the depth and scope of their “Streaming Theater Services.” Once again, thanks for your significant contributions to “the secular movement of blogging.”

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  • Clifford

    It’s nice to know that Nick has survived being away from the excellent surfing conditions of his student days here in Southern California. One of the last times I saw Nick over here I was picking him up from his pad in Venice to take him to the airport…. and we had to figure out how to get his huge surfboard into my car! We got to the airport late and I have this great memory of him running through the terminal with a giant rucksack on his back and the long (9ft?) surfboard under his arm….priceless.

    Wish I could be at his lectures…..they’ll be really good.


  • Nick Halmagyi

    Hey Clifford, I think you’re a bit mistaken,
    my surfboard is only 7ft, I’m 9ft.


  • Clifford

    I stand corrected. I remember you being 12 feet tall. It must have been a trick of the brighter sunshine.


  • Plato

    Hopefully the series will make full use of the web. I was thinking of the Perimenter Institue, in relation to the Compton Lectures?

  • Cynthia

    Sean- Why would “time probably run out” prior to threading the connection between strings and reality? Halmagyi is giving eight full lectures in order to thread this connection between strings and reality. As to the question of string’s role in reality, I am sorry to have to miss the “threading” of Halmagyi’s affirmative response to this question!

  • Sacha Blumen

    “He speaks with a distinct Australian accent, but it’s usually possible to understand him.” Hey, some of us Australians say similar things about Americans!

    Actually, it was when I was at a Group theory methods in physics conference in Paris that I became painfully aware of how difficult an Australian accent can sound – one French guy (who spoke English fairly understandably) said to me that he often found it very hard to understand Australians. I immediately tried to improve the clarity of my talking, but found it quite difficult.

    It’s interesting that knot invariants pop up in string theory (from this paper that Nick co-wrote):

    Is there much significance to the appearance of knot invariants in string theory? As a mathematician, I know about knot invariants and 3-manifold invariants from the quantum group point of view, I don’t know much from the Chern-Simons point of view. Are there problems in physics that can be solved using knot invariants derived from quantum (super)groups?

  • Nick Halmagyi

    It may comfort people to know that I have an assistant on hand who will provide an interpretive dance should my accent prove too baffling.

    regarding webcasting, I don’t imagine it happening any time soon at EFI. Although… there is a gentleman in the crowd who is taping this series, so perhaps some kind soul may volunteer to convert it to the relevant format and arrange the bandwidth etc. I will enquire with our local computer afficionados.


  • Cynthia

    Nick, thanks for responding. However, I must point out that EFI already has a huge archive of – publically available – webcast lectures via Fermilab Media Services.

  • Sean

    Cynthia, the Enrico Fermi Institute has no connection with Fermilab, so there is no archive of webcasts from EFI.

  • Nick Halmagyi


    the version of string theory where Chern-Simons theory emerges is topological string theory. This is initially obtained from a supersymmetric string theory but one trades in the supersymmetry generators in order to topologicalize the theory. I dont know of any useful circumstance where the super version Chern=Simons theory emerges, no doubt if it did, quantum supergroups would be relevant.

    In answer to your question: there is much significance in the appearance of knot invariants, Marcos Marino has several excellent reviews


  • Peter Woit

    Umm, I’m all for efforts to promote the better understanding of physics among the wider public, but given the heavy promotion of string theory over the last twenty-plus years, is this kind of thing really helpful? Claiming that string theory is anywhere near explaining dark energy and dark matter seems to me to be highly misleading, and there has already been a huge amount of this kind of hype going on for many years. I do notice that there seems to be no attempt to claim that string theory will explain the standard model.

  • Sacha

    Thanks for the link Nick, I’ll have a look at it :-)

    If super-Chern-Simons theory ever appears, you’ll be happy to know that people have created knot invariants from quantum supergroups – eg people at the University of Qld (Mark Gould, Jon Links, Ruibin Zhang, Tony Bracken etc) in the early 90s, and more recently Nathan Geer.

    It’s pretty easy to do once you have an R-matrix for a rep of a quantum supergroup – you just “follow the recipe”.

  • Jack

    Peter, Sean did say that “time will probably have run out” by the time string theory connects with reality. And don’t forget that when Sean talks about time, he means cosmic time. :-)

    Anyway, note that the title of the talks speaks of a “view towards reality”. That seems suitably modest to me. Perhaps you would do better to wait to see what he has to say before passing judgement?

  • Jack

    About the Australian accent: the problem with Australians is that it is not possible to understand what they say. The problem with Americans, by contrast, is that it is.

  • Plato

    Click on name

    Along with the introduction by presentation of the Compton Lectures to string theory, for lay people, I thought it important that some information also be assimilated, about what a “good theorist” might be, and what they have to know.

    Where would we be(independant and whole) without good teachers, thoughtful parents? :)

    Everyone thinks about our “young students,” but does not necessarily think about the “young minds” in those advancing with age? Does senility really overtake those who might have a open mind to learning? Possibly, ingenuity knows no age?

    Imagine a layman cane striking the scientist’s door with a theory in hand.:)


  • vengoroso

    Hey, sorry for the Spanish trackback. Usually they (trackbacks) don’t work in our serrver, but maybe I did something different this time 😛

    We are a group of pre- and post-docs working in different areas in math (from nc. geometry to PDE’s to rep theory) supposed to be based in the Univ. of Granada (Spain), though we are a bit spreaded over the world right now. Some of us are pretty interested in connections arising between math and modern physics, and so I proposed my mates to read Nick lectures in a regular basis and discuss about them on our blog.

    We also read “Not Even Wrong”, but as pure mathematicians we are not in te right position to argue on the validity of String Theory (nor any other modern physics, btw). Still, I personally find really interesting the idea of popolarizing the nowadays science, even if it is a controversial one.


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About Sean Carroll

Sean Carroll is a Senior Research Associate in the Department of Physics at the California Institute of Technology. His research interests include theoretical aspects of cosmology, field theory, and gravitation. His most recent book is The Particle at the End of the Universe, about the Large Hadron Collider and the search for the Higgs boson. Here are some of his favorite blog posts, home page, and email: carroll [at] .


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