A Busy Couple of Weeks

By Mark Trodden | March 5, 2006 9:43 pm

Well, I’ve been an exceedingly bad blogger recently. I’ve been posting very infrequently, but hope to get back to regular posts very soon. Life has been ridiculously busy over the last few weeks. A combination of trying to keep up with a number of different projects that I’m involved with, the first exam in my class PHY312 – Relativity and Cosmology, interviewing faculty candidates for a search that I’m on the committee for, and travel, have made it very hard to get around to posting.

By way of completing my excuse, and easing myself back into posting, let me explain why his last week was a classic case in point. Over the weekend and last Monday, I wrote the exam for my class, edited the draft of a paper, did some editorial work for the New Journal of Physics and worked on preparing a new colloquium.

I’ve been giving what I think is a nice colloquium called Connecting Cosmology and Fundamental Physics, and sometimes (with a few tweaks) called Connecting Cosmology and Colliders, for the past year or so. However, as I’ll explain soon, I needed to write a new one. On Tuesday I worked on a couple of papers and spent some time with my graduate student going through a problem. I also taught a review session for my class and held office hours. Then, that evening, I flew to Chicago, picked up my rental car and drove out to my hotel near Fermilab.

This was to prepare for Wednesday, when I was giving the Fermilab Colloquium (the new one I’d been writing), called Is Cosmic Acceleration Telling Us Something About Gravity? The talk begins with a summary of the evidence for the accelerating universe, then surveys the popular approaches to the problem. The last 25 minutes or so are then an explanation of the various issues involved in thinking about modifications to General Relativity as possible origins for cosmic acceleration. I illustrate this by describing some of my own work (with Sean and other collaborators) on modified gravity, which has been discussed on this blog and others a number of times.

I had a tremendous time at Fermilab. Firstly, I know a lot of people there, both in particle theory and astrophysics, and it’s always great to see them and discuss physics with them. Secondly, my host – Scott Dodelson (if you’re in the field, read his cosmology textbook – it’s fantastic!) – arranged for me to have a tour of the Silicon Detector (SiDet) Center, where work for for the D0 and CDF experiments was done, where work for detectors at the upcoming Large Hadron Collider (LHC) is ongoing, and where R&D for the proposed Dark Energy Survey is being carried out. Not only does one learn a lot touring a place like this, but one (at least me) truly realizes how relatively ignorant one is of the details of the wonderful and highly technical work that goes into making modern physics experiments work.

After a lovely dinner with friends old and new from Fermilab (Scott, Rocky, Dan, Mark, …), I drove back to O’Hare and spent the night in a hotel there in order to take the first flight back to Syracuse on Thursday morning,

This was in order to get to the Department in time to interview a faculty candidate who was spending a couple of days visiting Syracuse. After a couple of hours, I then jumped back into my car, drove home, picked up Sara and headed back to the airport to fly to North Carolina for my Sister in Law’s wedding.

Except for a scary bag delay (dresses, suits, etc…) we had a wonderful time over the last three days, and finally returned to Syracuse a couple of hours ago. I’ll now be back in town for five days, before Sara and I head out to California over Spring Break, to enjoy LA and Santa Barbara and, much more importantly, to attend the wedding of our good friend Don Marolf. It’ll be great to take a bit of a vacation, tour some wineries, see friends and generally relax!

Before I get there though, I’ve got a busy week ahead, but hope to get back to regular blogging anyway.

CATEGORIZED UNDER: Internet, Miscellany, Travel
  • Science

    Mark, that question about connecting cosmic acceleration and gravity is very interesting. Quantum field theory experts I know a little seem to be (almost) proud to say they know little about cosmology (beyond nuclear reactions in the first 3 minutes). However, as Eddington said, the ratio of electromagnetic to gravitational force is a “cosmological” sized number…

  • http://countiblis.blogspot.com Count Iblis

    Mark, in the near future it will be easier to blog for you see here. All you have to do is think about it and the posting will appear on the blog.

  • http://eskesthai.blogspot.com/2006/03/hands-on-cern.html Plato

    Hey Count,

    And maybe a few modifications with that same future?

    If it was possible to become free of negative emotions by a riskless implementation of an electrode – without impairing intelligence and the critical mind – I would be the first patient.

    Dalai Lama (Society for Neuroscience Congress, Nov. 2005)

    As I mentioned elsewhere, Iscap is a idea whose time has come, and recognition of the micropespective world, now joined with the cosmological understanding.

    As a layman, there is nothng more exciting then seeing this unification taking place.

    In what, we can percieve in the immediate environs, given the understanding, that this process of reductionism, can be reduced, and moved to the grand scheme of relativity? That, from natural processes, associative cosmological happenings, from collider experience.

    No sense linking here if one is not ready to explore the possibility of “new physics?” Ready to look at cosmology, with an all inclusive “geometric perspective,” whatever this may be?

    We needed to understand the physics involved, and if you didn’t have this, sure we’ll just ponder geometric relations, without ever making them inclusive?

  • http://eskesthai.blogspot.com/2006/03/hands-on-cern.html Plato

    “Nothing to me would be more poetic; no outcome would be more graceful … than for us to confirm our theories of the ultramicroscopic makeup of spacetime and matter by turning our giant telescopes skyward and gazing at the stars,” Greene said.

    You don’t have to be from any particluar “camp” to understand the implications of these words, without assigning them to some agenda?

  • Science

    Plato: I disagree! If nature was inherently poetic and graceful, there would hardly be wars, starvation, disease, etc. People who write novels and film scripts are full of beautiful ideas and happy endings. The world simply isn’t like that. Don’t try to force your poetry on to natural science. High expectations create prejudices, and scientists have to be prepared to accept the most simple theory that explains the facts, even if it looks vulgar.

  • http://eskesthai.blogspot.com/2006/03/hands-on-cern.html Plato

    I wasn’t talking about all your other ideas:)

  • Science

    I just mean LQG. Greene is prejudiced in favour of string theory, which is fine if he keeps scientific, but we don’t need emotional brainwashing to spread prejudice in science.

  • Life is LIke a Box of

    Pick one. Sure. It doesn’t matter.

    Nothing emotional about the future of cosmology and of physics of reductionism together?

    Okay. So you don’t get emotionally involved.

    It’s still science.

    And that’s all I got to say about that. :)

  • Jim Graber

    Hopefully some ppt or pdf of your talk will soon be available on this website
    or elsewhere?
    Congratulations to your friends on their weddings etc. but I would really like to see some physics after this tantalizing hint.

  • Shantanu

    I went through the transparencies of your talk at FNAL . I have a naive question.
    (which I am sure is discussed in some of your papers) you cited.
    the class of modified gravity models which you are considering
    to account for Dark energy(eg CDTT) and that in astro-ph/0410031 , do these models obey strong equivalence principle?

  • Shantanu

    Mark or Sean, could you tell me what is the answer to question # 10?

  • http://blogs.discovermagazine.com/cosmicvariance/sean/ Sean

    Sorry, Shantanu, I missed your question earlier. No, these theories generally do not obey the strong equivalence principle, since the behavior of gravity depends on the background; they are much like Brans-Dicke theories that way. But really it’s better to forget about the equivalence principle and think about Lagrangians.

  • shantanu

    Thanks, Sean for the answer . I find it difficult to intute stuff from Lagrangians, (but that’s just me.)
    Also one more general quesion about all these modifed gravity
    theories used to explain dark energy such
    as DGP, CDTT and even those which are used to explain away dark matter
    such as MOND/TeVss . Won’t these theories also affect physics of compact
    objects such as neutron stars , black holes with possibly
    some observable consequences which could be tested? (or the physics for such compact objects same as GR for thse modified gravity theories.) I haven’t seen any of these theories address physics of compact objects. But perhaps you or others could clarify.


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Cosmic Variance

Random samplings from a universe of ideas.

About Mark Trodden

Mark Trodden holds the Fay R. and Eugene L. Langberg Endowed Chair in Physics and is co-director of the Center for Particle Cosmology at the University of Pennsylvania. He is a theoretical physicist working on particle physics and gravity— in particular on the roles they play in the evolution and structure of the universe. When asked for a short phrase to describe his research area, he says he is a particle cosmologist.


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