Loops 05, this year's big LQG conference

marcus

http://loops05.aei.mpg.de/index_files/Home.html

October 10-14 at Potsdam, Albert Einstein Institute

The aim of this conference is to summarise the status and open problems of the various approaches to quantum gravity and to present new ideas and research directions.

"The topics of this conference will include:

Background Independent Algebraic QFT
Causal Sets
Dynamical Triangulations
Loop Quantum Gravity
Non-perturbative Path Integrals
String Theory"



International Organising Committee

Abhay Ashtekar (USA)
John Baez (USA)
John Barrett (UK)
Alejandro Corichi (MEX)
Fay Dowker (UK)
Laurent Freidel (FR and CA)
Chris Isham (UK)
Jurek Lewandowski (POL)
Renate Loll (NL)
Hugo Morales Tecotl (MEX)
Alejandro Perez (FR)
Jorge Pullin (USA)
Carlo Rovelli (FR)
Lee Smolin (CA)
Rafael Sorkin (USA)


Local Organising Committee
(Albert Einstein Institute, Potsdam, Germany)

Dorothea Bahns
Benjamin Bahr
Martin Bojowald
Johannes Brunnemann
Bianca Dittrich
Kristina Giesel
Hermann Nicolai
Thomas Thiemann

marcus

http://loops05.aei.mpg.de/index_files/Home.html
October 10-14 at Potsdam, Albert Einstein Institute
More about the programme
http://loops05.aei.mpg.de/index_files/Programme.html

"The topics of this conference will include:

Background Independent Algebraic QFT
Causal Sets
Dynamical Triangulations
Loop Quantum Gravity
Non-perturbative Path Integrals
String Theory"

A detailed programme will be available in July.

Invited Speakers will include:
Abhay Ashtekar (USA)
John Baez (USA)
John Barrett (UK)
Alejandro Corichi (MEX)
Robbert Dijkgraaf (NL)
Fay Dowker (UK)
Laurent Freidel (FR and CA)
Karel Kuchar (USA)
Jurek Lewandowski (POL)
Renate Loll (NL)
Roy Martens (UK)
Hugo Morales Tecotl (MEX)
Alejandro Perez (FR)
Jorge Pullin (USA)
Martin Reuter (GER)
Carlo Rovelli (FR)
Lee Smolin (CA)
Rafael Sorkin (USA)
Stefan Theisen (GER)
Rainer Verch (GER)
----------------------------------
A footnote says it is still to be confirmed that Abhay Ashtekar will be giving one of the talks.
I see some string theorists are included in this list of invited speakers
Robbert Dijkgraaf
Stefan Theisen

marcus

[EDIT: the link to the the Loop 05 Programme page is
http://loops05.aei.mpg.de/index_files/Programme.html ]
I'm trying to understand the pattern of the main themes. And identify some of the invited speaker's interests. Notice that what has been called "spin foams" in the past is now given the more descriptive heading "non-perturbative path integrals". the interesting current work of Laurent Freidel would, I expect, come under that rubric.

The most important unstated topic, or issue, is COSMOLOGY and in particular the issue of the BOUNCE. A number of the invited speakers have written papers about (loop and other) quantum cosmology, but this is not explicitly made a theme.

The 6 stated topics of the conference, with a few names tentatively associated with each line of research, are

1. Background Independent Algebraic QFT
Jurek Lewandowski(?), John Baez(?), also Rainer Verch---see his http://arxiv.org/abs/math-ph/0112041

2. Causal Sets
Fay Dowker, Rafael Sorkin

3. Dynamical Triangulations
Renate Loll

4. Loop Quantum Gravity
4A hamiltonian LQG
4B consistent discretization LQG---Jorge Pullin, Karel Kuchar(???)

5. Non-perturbative Path Integrals
Laurent Freidel, Alejandro Perez

6. String Theory
Robbert Dijkgraaf, Stefan Theisen

[EDIT I have to leave this post unfinished, with some names not assigned or only tentatively assigned, in some cases with question marks.]

Topic 0. unstated, is cosmology and some invited speakers who have research interest in that topic are:
Roy Martens ,
Hugo Morales Tecotl,
Martin Reuter

As this PF thread by wolram
http://www.physicsforums.com/showthread.php?t=75354
emphasizes, Jorge Pullin pursues a QG approach called consistent discretizations which gets rid of the hamiltonian constraint (by variable step discrete time evolution). In order to fit that into the list of topics, I have had to break topic 4 into two subheadings 4A and 4B.

Here is a list of invited speakers
Abhay Ashtekar (USA)
John Baez (USA)
John Barrett (UK)
Alejandro Corichi (MEX)
Robbert Dijkgraaf (NL)
Fay Dowker (UK)
Laurent Freidel (FR and CA)
Karel Kuchar (USA)
Jurek Lewandowski (POL)
Renate Loll (NL)
Roy Martens (UK)
Hugo Morales Tecotl (MEX)
Alejandro Perez (FR)
Jorge Pullin (USA)
Martin Reuter (GER)
Carlo Rovelli (FR)
Lee Smolin (CA)
Rafael Sorkin (USA)
Stefan Theisen (GER)
Rainer Verch (GER)

marcus

When it comes time to talk about consistent discretizations, Jorge Pullin is apt to mention this paper
http://arxiv.org/abs/gr-qc/0212033
because it says something unusual about (a major current focus of interest) the BOUNCE.

What they say there has a bearing on the CNS thread
http://www.physicsforums.com/showthr...628#post564628
so I added some discussion of it to that thread.

Smolin has deduced observable (falsifiable) consequences from the CNS hypothesis that the physical constants can change ever so slightly during a bounce----where gravitational collapse results in re-expansion. this however is only an hypothesis, for Smolin. he has not proposed any mechanism which would allow the parameters of physics to change slightly during collapse and re-expansion

However those dark horses, Rodolfo Gambini and Jorge Pullin, have very tentatively described how such a thing might happen, if in fact it does happen, in this paper. It is intriguing, if only because AFAIK no one else has proposed any idea filling that spot in the gravity jigsaw puzzle

Discrete quantum gravity: applications to cosmology
Rodolfo Gambini, Jorge Pullin
19 pages, 9 figures
Class.Quant.Grav. 20 (2003) 3341

"We consider the application of the consistent lattice quantum gravity approach we introduced recently to the situation of a Friedmann cosmology and also to Bianchi cosmological models. This allows us to work out in detail the computations involved in the determination of the Lagrange multipliers that impose consistency, and the implications of this determination. It also allows us to study the removal of the Big Bang singularity. Different discretizations can be achieved depending on the version of the classical theory chosen as a starting point and their relationships studied. We analyze in some detail how the continuum limit arises in various models. In particular we notice how remnants of the symmetries of the continuum theory are embodied in constants of the motion of the consistent discrete theory. The unconstrained nature of the discrete theory allows the consistent introduction of a relational time in quantum cosmology, free from the usual conceptual problems."

arivero

Here there is a common point between Strings and LQG. As of today, neither Loops '05 nor Strings '05 have specified its schedule.

http://www.fields.utoronto.ca/progra...5/program.html
http://loops05.aei.mpg.de/index_files/Home.html

I can understand about the minor talks. But the plenary sessions?

marcus

this is actually a point of contrast, not similarity, Alejandro.

Loop 05 is scheduled for October 10-14 and plans to post the programme in July----that is, 3 months in advance of the conference. (their list of invited speakers for the plenary sessions is already posted, but not the titles of the talks)
If you want advance information about the programme, don't just go to the Home page that you linked to, but go also to the Programme page:
http://loops05.aei.mpg.de/index_files/Programme.html

By contrast, in the case of String 05, it is already only 2 months before the conference, scheduled for July 11-16, and we do not even see a list of invited speakers.
the schedule, as you point out, is a complete blank:
http://www.fields.utoronto.ca/progra...5/program.html
However they do advertise a panel discussion on "The Next Superstring Revolution"
http://www.fields.utoronto.ca/progra...005/panel.html

marcus

Rafael Sorkin's name just came up in another thread. I noticed him on the list for the Loop 05 international organizing committee, and also on the list of Loop 05 invited speakers, partly because this is one of this year's important conferences and Sorkin is one of the FEW AMERICANS.
If you look at the leading edge of theoretical physics (not at the lame duck boondoggles but the research going somewhere important) what is the US representation?

The US used to lead in theoretical physics, right? or am I mistaken?

Now I am looking at the list of those giving plenary talks at Loop 05. As of today I see that all 20 are confirmed

AFAIK 3 are US born: john baez, lee smolin, rafael sorkin

AFAIK only 2 are US-born and still in US. Lee Smolin is an expatriate---lives and works in Canada.

So 2 out of the 20 invited speakers. Ten percent.

Even if you count all USA participants including those born and educated abroad and who now live here, it is not a big percentage. Quantum gravity is the foremost problem in theoretical physics, this is the main QG conference of the year, and the US participation does not look so impressive compared with the Netherlands, say, or even the rest of North America (combining Canada and Mexico)

It is possible that the string fiasco cost US some lead in theoretical physics.

Misallocation of research efforts can conceivably do that. It would be something to check up on a few years down the line.

Chronos

What a terrific, blue ribbon list of speakers! I look forward to what comes out of that gathering. It's a veritable who's who list in theoretical physics.

selfAdjoint

Well, the US was so strong in string physics, the Europeans sensibly went in for something else. I think QG triumphalism, and selling strings short, is a little premature here though. These folks have still to demonstrate that their own program is more than pie in the sky. They have produce no better segue to the standard model than strings have, and that is still the gold standard of observable physics.

marcus

that sounds like an idea. I wish some major US physics departments had done the same (since Harvard, Princeton, UCSB were already so strong). We could have used a little diversification of the portfolio right here at home.

I have not heard any triumphalism (comparable to string hype) from the QG people. Have you?
Also I hear almost no comment by QG people about the string fiasco. The strongest negative comment about string that I have heard comes from third parties or from string theorists themselves: Philip Anderson, Paul Steinhardt, Lubos Motl (comparing Landscape theorists to a drunk looking for his car-keys in the middle of the ocean on the surface), Peter Woit, Sheldon Glashow.

I urge you to make a sharp distinction between cheers for recent developments in QG (like the Causal Dynamical Triangulations papers of Ambjorn Jurkiewicz and Loll, which it is only natural to cheer about) and selling String short. They are two separate and independent activities. And I happen to engage heartily in both.

If String were a stock, I would have advised selling it short a year ago, and we would all be making a bundle right now.

I think it would be reasonable to say that the gold standard which a QG theory like CDT (or Loop) must measure up to is not the Std. Mdl. but instead GENERAL RELATIVITY.
In other words, the QG theories are not a rival to string (in the sense of trying to explain particles and forces) they are merely an invidious comparison. It is just a coincidence that QG theories have been making significant progress of late, while String has not been. One should remember that they are not aiming at the same target.

However once people have a good background-independent model of spacetime and its geometry, maybe they will get some clues from it about the right way to lay on the matter fields. maybe. no promises. the realistic goal now is not a "theory of everything" but just a better model of spacetime that reproduces Gen Rel at large scale

arivero

On other hand
http://wwwth.mppmu.mpg.de/members/blumenha/program.html

selfAdjoint

Nice riposte.

marcus

there the conference date is June 13, which is only three weeks away, as of tomorrow, so they damn well better have their schedule of talks posted!

it is interesting to see the programs of major conferences like this, as a gauge of where the field is going. thanks Alejandro, you posted the program for this:

the June 2005 String Phenomenology conference
http://wwwth.mppmu.mpg.de/members/blumenha/main.html

the whole idea of "String Phenomenology" may be a bit on the wishful thinking side---phenomenology is normally relevant only where a theory predicts something and can be tested by looking for observable effects.
but, lacking anything better to do, particpants can discuss the LANDSCAPE and indeed that seems to be what this StringPhen conference is largely about!

In any case the Phenom. conference is 3 weeks off and they have their programme posted. Except that 18 of the speakers have not yet posted the titles of their talks

the other string conference you cited, Strings 05, is the real oddity here. it is 7 weeks away and they have not posted any Programme at all!
http://www.fields.utoronto.ca/progra...5/program.html
As of today this is a complete blank (no speakers no titles) except for one evening panel discussion called "The Next Superstring Revolution".
I agree this looks peculiar and may be symptomatic of some difficulty or general indecision

It will be interesting to watch. I'll be curious to see the extent to which the conference is dominated by Landscapers. Lubos blog got on the case of Landscape-string again today. but wording was more polite and less flamboyant than before he got a warned (by the authorities presum.)

marcus

Alejandro called my attention to an interesting aspect of this year's string conference scene.

String 05, Alejandro points out, has not posted the titles of any talks, or even a list of speakers, although the conferences is only 7 weeks away!

Along the same lines, the June 2005 String Phenomenology conference is only 3 weeks off, and there are no titles posted for the talks of 18 of the speakers, as of today.
http://wwwth.mppmu.mpg.de/members/blumenha/main.html

http://wwwth.mppmu.mpg.de/members/blumenha/program.html

the apparent indecision about who and what could be symptomatic of something---a shift, a sea-change, a period of confusion as to what one should be talking about?----it is hard for me to tell.

it is very different from the Quantum Gravity conferences I have seen materialize in recent years, where the list of speakers and the topics of their talks were already posted well in advance of the conference
this goes for conferences that we have discussed here at PF that took place in Potsdam, in Marseille, in Poland, in Mexico, at Perimeter. One was able to study the list of titles considerably longer ahead of time and often get a reasonable notion of the content.

The Phenom. conf. begins June 13. The 18 speakers for whom talk titles arent yet posted (as of today) include some prominent folk like Renata Kallosh. I will list them:

Bethke
Kiritis
Trivedi
Quevedo
Renata Kallosh
Gary Shiu
Acharya
Derendinger
Antoniadis
Marchesano
Mayr
Angelantonj
Reffert
Gmeiner
Dall'Agata
Rabinovici
Conlon
Gray

arivero

Hmm I was parrying myself, actually. It was not my intention to trick Marcus into a too short lunge.

marcus

fencing is your sport, Alejandro
but here, in this, we are hardly adversaries
instead I think we are cooperatively scratching each other's backs
(at least I aspire to be helpful to you, as you are to me!)

marcus

seriously, I hope you got something from the program that I flagged of the October 14 "Loops 05" conference at Potsdam (still incomplete as it is)

and I certainly was glad to see what is available for the June Phenom. conference in Munich, and the July "Strings 05" in Toronto. I would not have been likely to find those by myself---so wouldnt have seen them had you not flagged them for me.

What stands out in my mind about the October Potsdam conference is this list of topics (rather differerent emphasis from those of Marseille May 04 just last year!). I'll remind us of it:

Topics of Loops 05:

"Background Independent Algebraic QFT
Causal Sets
Dynamical Triangulations
Loop Quantum Gravity
Non-perturbative Path Integrals
String Theory"