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.
March 6th, 2006 at 4:53 am
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…
March 6th, 2006 at 8:57 am
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.
March 6th, 2006 at 10:09 am
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?
March 6th, 2006 at 1:11 pm
You don’t have to be from any particluar “camp” to understand the implications of these words, without assigning them to some agenda?
March 6th, 2006 at 1:28 pm
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.
March 6th, 2006 at 1:32 pm
I wasn’t talking about all your other ideas:)
March 6th, 2006 at 4:04 pm
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.
March 6th, 2006 at 4:27 pm
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.
March 6th, 2006 at 5:15 pm
Hopefully some ppt or pdf of your talk will soon be available on this website
http://www-ppd.fnal.gov/EPPOffice-w/colloq/colloq.html
or elsewhere?
Congratulations to your friends on their weddings etc. but I would really like to see some physics after this tantalizing hint.
Best,
Jim
April 15th, 2006 at 3:00 am
Hi
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?
April 17th, 2006 at 8:37 pm
Mark or Sean, could you tell me what is the answer to question # 10?
Thanks
April 17th, 2006 at 8:43 pm
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.
May 2nd, 2006 at 10:37 pm
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.
Thanks