Friday, May 08, 2009

A Day at the APS April Meeting

The APS April meeting was in May. Is that an indicator for climate change? I squeezed in the trip to Denver, as previously mentioned, to give a talk about 'Phenomenological Quantum Gravity' and to be on a panel discussion about women and minorities in physics. The meeting took place at the Sheraton Downtown Denver - not exactly the class of hotels I usually stay in. It's the kind of place with guys in fancy uniforms at the entrance that insist on taking your bag, and with an army of service personnel that probably help you with anything your heart desires to make your stay more pleasant - if you speak Spanish. The room had a huge LCD screen. But no mini-bar. Maybe I shouldn't have used the groupcode from the APS meeting.

The plenary session on Tuesday morning was quite interesting. First thing in the morning, Paris Sphicas gave a short pep-talk on LHC physics and the current schedule. However, I think you are better up-to-date by reading Peter's blog. Sphicas further talked about some early data analysis that had been done with cosmic rays and from last year's first cycling of the beam. What I gathered is that the detectors work well and everybody is excited about moving on. 

The next talk was by James Cronin, winner of the Nobel Prize in Physics 1980 (for the co-discovery of CP violation in the kaon system). He talked about the Pierre Auger Cosmic Ray Observatory and new data that they had (some of which he apparently wasn't supposed to show). It seems that with more events and better statistics the correlation between active galactic nuclei and the sources of cosmic rays - on which I reported here and more details here - has become weaker, and the distribution of cosmic rays looks more isotropic now than with the first measurements. 

The last plenary talk of the day was by Raymond Fonck about progress in understanding and managing plasma turbulences and the ITER project.  I think it is one of the most relevant topics in physics one can presently work on. Power generation from nuclear fusion has the potential to become the energy supply of the future. However, even if we finally manage to deal with it, it will take too long to make the technique practicable to help us with the energy problems we are currently facing, so it's certainly not the only thing we should be doing.

The  session in the afternoon that I was speaking in was chaired by Vicky Kalogera from Northwestern University. The first talk was by Andrea Lommen who spoke about detecting gravitational waves with pulsars. The idea is that the signals received from pulsars have a reasonably precise timing over many years, and distortions of the background geometry through gravitational waves - generated eg by a nearby black hole merger - might affect that timing and become measurable. I was distracted and quite impressed by her body language, wondering where one can take a class to dance the figure of the rotating pulsar. It turned out later she had previously been a professional dancer. 

My talk was a brief summary of various ways to approach the challenging problem of measuring effects of quantum gravity. While I didn't have time to go into details I hope I managed to provide a sense of how the field is developing. The questions afterwards were really interesting. Even though it wasn't content of my talk, we were discussing Craig Hogan's "Holographic Noise" for a bit, and I was relieved to hear that the audience seemed to share my scepticism (see earlier post for details). 

The last talk in the session was by Steve McGuire about material science in the LIGO experiment, followed by a panel discussion in which the three speakers introduced themselves and we spoke for a while about our different experiences with making our ways in science, then taking some questions from the audience. It was both more interesting and more useful than I was afraid it would be, for discussions about minority questions have a tendency to heat up quickly. Instead, it was a very constructive exchange that showed there are many different paths one can take and options one can use and that after all what matters is your dedication to your work and how much you love science. It's good to be reminded of that occasionally and I am glad I went to the meeting.


  1. I read this morning of geologists discovering "gravitational waves" above mountains, and that gravitational waves were almost routinely observed. Surely this must be a different use of the term gravitation waves than physicist use? what are the geologists talking about?

  2. Hi JSMeyer,

    I guess the kind of waves that you read about is what usally is called "gravity waves", which occur at the boundary layer between different fluids/gases under the influence of gravity.

    Best, Stefan

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  4. Thank you, Stefan and others. I evidently replaced the word "gravity" with "gravitation" in my usual a.m. stupor.

  5. Speaking of waves, if you can get to this Maya Lin composition here - Storm King Wavefield

    it looks lovely. Just like gravity waves :)

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  7. thank you, Plato. I should have figured that out myself . You are very kind.

  8. Hi Bee,

    Thanks for the run down on the meeting and as it appears you where kept quite busy. It’s interesting what Andrea Lommen is attempting with using pulsars as a universal metronome and I’ m now curious what in total you meant by her body language and dance as it relates to her presentation.


  9. Hi Arun,

    Interesting, yet for me what this artist presents seems to better represent standing waves rather than ocean ones. Perhaps the mountains beyond are what is to account for this in acting as a barrier to create this effect :-)



  10. Phil, I was wondering too. Might it be a twirl on stage while explaining ?

    Yes of course in terminology-Gravitational wavesSome previous posts you too had written in relation.

    1.Gravity Waves in the Sky 2.Indirect Detection of Gravitational Radiation I was concerned that I might be injecting to much of my own perspective(removed first comment) in the first link(1) under discussion.

    While it is more then the attempt to use the word "gravity" Stefan, once "weathered in relation" was used, I of course, was injecting a philosophical point of view about the dynamics in the cosmos under WMAP idealizations, hence here are Brian Greene's words.

    "In a sentence, the observations are spectacular and the conclusions are stunning," said Brian Greene of Columbia University in New York City. "WMAP data support the notion that galaxies are nothing but quantum mechanics writ large across the sky." "To me, this is one of the marvels of the modern scientific age." Bold added by me for emphasis.

    Wayne Hu's work then became important and to Phil's points, I thought that might be explained in perspective about WMAP as well?

    It is okay to be skeptical about Craig Hogan's "Holographic Noise." :)

    Our view of the universe is about to change forever. Since science began, all our knowledge of what lies above, below and around us has come from long-familiar forms of energy: light, produced by distant astrophysical objects; and matter, in the form of particles such as cosmic rays. But we are now in a position to study the universe using an entirely different form of energy that until now has never been directly detected – gravitational waves. Sounding out the Big BangBest,

  11. The road to Stokes then is an ultimate realization that is current with research today. The Quark Gluon Plasma?

    With the discovery of sound waves in the CMB, we have entered a new era of precision cosmology in which we can begin to talk with certainty about the origin of structure and the content of matter and energy in the universe.Wayne Hu
    One tends to get a sense of what people like Sean Carroll are doing. How dynamical Tegmark might be in terms of what the universe is doing mathematically and melodically. Shape?

    Navier-Stokes Equation?

  12. The < - br- > button needs to be turned on for spacing between quotes and further words, typed by whoever?


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