GRAVTUM II, Amorgos 08
September 14-20, 2008
Organizer
C. Chryssomalakos
Instituto de Ciencias Nucleares, UNAM, Mexico
chryss@nucleares.unam.mx
Scope
The theme of the meeting loosely revolves around the interface of the quantum with the gravitational, but inspired digressions would certainly be welcome. The emphasis is on the exchange and thorough discussion of ideas, even half-baked ones, rather than on the presentation of polished results. The format is to be based mostly on a few "inspirational" blackboard talks (no projectors of any sort...), of longer than the usual duration (~ 90' -- 120'), followed by discussions, establishing all along new standards for informality. Some ideas that might be touched upon include the following:
Participants would be expected to contribute their own list of ideas, or even visions, and submit it to the scrutiny of the plenum, all under the unforgiving sun of the Aegean... They are in fact invited to forward, at their earliest convenience, a brief description, so that the above list can grow, and be shared in advance.
Conference Site
Like last year, the conference will take place in the village of Tholaria, near the port of Aeghiali (expect various spellings), on the island of Amorgos, in Greece --- the lectures will be at the Cultural Center of the village (see maps of Greece, Amorgos and Aeghiali region, and some photos of Amorgos).
Amorgos is the easternmost of the Cyclades, and one of the most mountainous of all Greek islands --- it has been continuously inhabited since at least the Neolithic Age (~4000 BC). There are some nice beaches to swim in, a beautifully preserved Chora (capital), the famous Chozoviotissa's monastery, founded in 1088, and excellent hiking (see, eg, an english, and a belgian site), with magnificent vistas extending to nearby islands. Tholaria has just over a hundred permanent inhabitants, and preserves a lot of the island character that once permeated the Aegean. People here still cultivate the land, raise farm animals, and fish for a living, but they might well be the last generation to do so.
C. Chryssomalakos
Instituto de Ciencias Nucleares, UNAM, Mexico
chryss@nucleares.unam.mx
Scope
The theme of the meeting loosely revolves around the interface of the quantum with the gravitational, but inspired digressions would certainly be welcome. The emphasis is on the exchange and thorough discussion of ideas, even half-baked ones, rather than on the presentation of polished results. The format is to be based mostly on a few "inspirational" blackboard talks (no projectors of any sort...), of longer than the usual duration (~ 90' -- 120'), followed by discussions, establishing all along new standards for informality. Some ideas that might be touched upon include the following:
- Quantum geometry on classical manifolds: The classical formulation of geometry employs concepts like that of a point or a line. In an operational approach to geometry, ie, one where geometrical quantities are defined in terms of experiments, the quantum nature of the probes (particles) at our disposal would also endow the perceived geometry with quantum characteristics. Shouldn't this aspect of geometry complement the more widespread noncommutative manifold paradigm?
- Noncommutative QFT: Considerable efforts have gone into the formulation of field theory on noncommutative manifolds, in an attempt to simulate quantum gravitational effects. Are there physical and/or mathematical arguments (eg, thought experiments, Lie algebra stability considerations, etc) that could pin down the form of noncommutativity?
- Quantum equivalence principle: what is the fate of this pillar of classical General Relativity in the quantum world? Are there "geodesics" quantum particles "follow"? How relevant is the center-of-mass concept in GR, or in a quantum context?
- Generalized symmetries and the
Planck scale: contrary to
statements to the contrary, an invariant length scale (in addition to the
invariant velocity of light) can be introduced within the Lie algebra
framework. What are the advantages and disadvantages of employing
non-linear schemes, as in DSR? Has the physical consistency of such
schemes been established?
Participants would be expected to contribute their own list of ideas, or even visions, and submit it to the scrutiny of the plenum, all under the unforgiving sun of the Aegean... They are in fact invited to forward, at their earliest convenience, a brief description, so that the above list can grow, and be shared in advance.
Conference Site
Like last year, the conference will take place in the village of Tholaria, near the port of Aeghiali (expect various spellings), on the island of Amorgos, in Greece --- the lectures will be at the Cultural Center of the village (see maps of Greece, Amorgos and Aeghiali region, and some photos of Amorgos).
Amorgos is the easternmost of the Cyclades, and one of the most mountainous of all Greek islands --- it has been continuously inhabited since at least the Neolithic Age (~4000 BC). There are some nice beaches to swim in, a beautifully preserved Chora (capital), the famous Chozoviotissa's monastery, founded in 1088, and excellent hiking (see, eg, an english, and a belgian site), with magnificent vistas extending to nearby islands. Tholaria has just over a hundred permanent inhabitants, and preserves a lot of the island character that once permeated the Aegean. People here still cultivate the land, raise farm animals, and fish for a living, but they might well be the last generation to do so.
Registration
For purely logistic reasons, the number of participants is limited to about 25. If interested in participating, please contact the organizer, supplying your name and affiliation, number of accompanying persons, and, when available, your travel details. A registration fee of 50 euros is payable in cash at the conference - the amount collected will be donated to the Cultural Center of Tholaria, where the talks are held, for much needed maintenance work. All costs related to attending the conference are to be covered by the participants - there is no external support for the event.
List of participants (+ titles and abstracts)
Chryssomalis Chryssomalakos (ICN UNAM, Mexico City)
On spacetime noncommutativity
Some ideas about possible origins for spacetime noncommuattivity will be reviewed, including algebraic stability arguments, representation theoretic ones, and even unorthodox invocations of molecular dynamics. The central role of spin will be highlighted, along with the miraculous localizing effect of negative energy states. The main question I would like to see probed is whether spacetime noncommutativity could be something more than a regularization gimmick.
Alioscia Hamma (Perimeter
Institute,
Waterloo)Some ideas about possible origins for spacetime noncommuattivity will be reviewed, including algebraic stability arguments, representation theoretic ones, and even unorthodox invocations of molecular dynamics. The central role of spin will be highlighted, along with the miraculous localizing effect of negative energy states. The main question I would like to see probed is whether spacetime noncommutativity could be something more than a regularization gimmick.
Hector Hernandez (ICN UNAM, Mexico City)
Jerzy Kowalski-Glikman (ITP, Wroclaw)
Deformed particle
dynamics from (quantum) gravity?
In my talk I will first argue that the ``no gravity limit" of 4d quantum gravity coupled to point particles can be described by Chern-Simons theory with SO(4,1) gauge group on boundary of space-time, being a product of two-sphere and real time axis. The particles are represented by charged punctures on the sphere. Then by using the Alekseev-Malkin construction I will derive the effective symplectic structure of the particles. This symplectic structure happens to be very mildly deformed by the presence of gravity. In particular there seem to be no obvious traces of kappa-Poincare structure. I will speculate in which circumstances kappa-Poincare may arise.
Alejandro Perez (CPT, Marsaille)In my talk I will first argue that the ``no gravity limit" of 4d quantum gravity coupled to point particles can be described by Chern-Simons theory with SO(4,1) gauge group on boundary of space-time, being a product of two-sphere and real time axis. The particles are represented by charged punctures on the sphere. Then by using the Alekseev-Malkin construction I will derive the effective symplectic structure of the particles. This symplectic structure happens to be very mildly deformed by the presence of gravity. In particular there seem to be no obvious traces of kappa-Poincare structure. I will speculate in which circumstances kappa-Poincare may arise.
Loop
quantum gravity: where are we now?
The basic building blocks defining the theory of loop quantum gravity will be presented. I will start by describing the special features of general relativity that make possible a classical formulation of gravity in terms of connection variables. Loop quantum gravity is the result of the implementation of a canonical background independent quantization recipe, known as the Dirac program, to this formulation. I will describe the implementation of the Dirac program to gravity in connection variables in some detail. This will provide us with the framework for discussing the open questions and difficulties that the program faces at its present stage.
David Rideout (Perimeter
Institute,
Waterloo)The basic building blocks defining the theory of loop quantum gravity will be presented. I will start by describing the special features of general relativity that make possible a classical formulation of gravity in terms of connection variables. Loop quantum gravity is the result of the implementation of a canonical background independent quantization recipe, known as the Dirac program, to this formulation. I will describe the implementation of the Dirac program to gravity in connection variables in some detail. This will provide us with the framework for discussing the open questions and difficulties that the program faces at its present stage.
Spacetime geometry
from fundamental discreteness
The causal set programme begins with a discrete set of ``atoms of spacetime'', and a partial order relation, of which the causal structure of spacetime is meant to be the macroscopic embodiment. One of the central questions is to deduce properties, such as dimension, topology, metric, of the macroscopic continuum from an underlying causal set. While many macroscopic quantities are relatively easy to reconstruct from the causal ordering, such as timelike distance and spacetime dimension, spatial distance is encoded in a more indirect manner. I will discuss some of the issues one encounters in attempting to extract spatial distance from a Lorentz invariant discrete causal order (causal set), and propose a method which circumvents these difficulties.
Daniel Sudarsky (ICN
UNAM,
Mexico City)The causal set programme begins with a discrete set of ``atoms of spacetime'', and a partial order relation, of which the causal structure of spacetime is meant to be the macroscopic embodiment. One of the central questions is to deduce properties, such as dimension, topology, metric, of the macroscopic continuum from an underlying causal set. While many macroscopic quantities are relatively easy to reconstruct from the causal ordering, such as timelike distance and spacetime dimension, spatial distance is encoded in a more indirect manner. I will discuss some of the issues one encounters in attempting to extract spatial distance from a Lorentz invariant discrete causal order (causal set), and propose a method which circumvents these difficulties.
Exploring
the Geometry on a Quantum World
We are used to think the world is endowed with a geometrical structure. We arrived to that conclusion by exploring it with what we thought were classical point-like particles. But now we know there are no such things, and we should thus acknowledge in the construction of our theories that all the objects we can explore the world with are both quantum and extended. I want to discuss the first steps of the exploration of what, if any, are the changes we need to make in our description of physical geometry in light of such acknowledgement.
Petros Wallden (Raman Research Institute, Bangalore)We are used to think the world is endowed with a geometrical structure. We arrived to that conclusion by exploring it with what we thought were classical point-like particles. But now we know there are no such things, and we should thus acknowledge in the construction of our theories that all the objects we can explore the world with are both quantum and extended. I want to discuss the first steps of the exploration of what, if any, are the changes we need to make in our description of physical geometry in light of such acknowledgement.
Anhomomorphic Logic
This is a new approach to Quantum Theory, realistic in flavour, that came as development of the decoherent histories approach and of quantum measure theory, and was initiated by Rafael Sorkin. It is believed as the way forward in constructing a quantum theory of causal sets (and thus many people are involved in both fields). In this approach, reality is a co-event, which is essentially an assignment of a truth value (True, False) to each question. The way this assignment is done, mimics classical physics in as much as possible, allowing however for sufficient flexibility to accommodate quantum paradoxes as it is shown by the analysis of Kochen-Specker theorem (F. Dowker and Y. Ghazi-Tababai). Here I will also talk about the issue of emergence of classicality and of how do probabilistic predictions arise in this framework.
Jorge Zanelli (CECS, Valdivia)This is a new approach to Quantum Theory, realistic in flavour, that came as development of the decoherent histories approach and of quantum measure theory, and was initiated by Rafael Sorkin. It is believed as the way forward in constructing a quantum theory of causal sets (and thus many people are involved in both fields). In this approach, reality is a co-event, which is essentially an assignment of a truth value (True, False) to each question. The way this assignment is done, mimics classical physics in as much as possible, allowing however for sufficient flexibility to accommodate quantum paradoxes as it is shown by the analysis of Kochen-Specker theorem (F. Dowker and Y. Ghazi-Tababai). Here I will also talk about the issue of emergence of classicality and of how do probabilistic predictions arise in this framework.
I expect to discuss what I think might
be a possible role for Chern-Simons theories in the description of the
spacetime geometry.
Program
| Monday |
Tuesday |
Wednesday |
Thursday |
Friday |
Saturday |
|
|---|---|---|---|---|---|---|
| 10:00 -- 11:30 |
D. Sudarsky |
Excursion |
J. Zanelli |
P. Wallden |
07:20 -- 15:00
Return trip to Piraeus |
|
| 11:30 -- 12:00 |
Coffee break | Coffee break | Coffee break | |||
| 12:00 -- 12:30 |
A. Perez |
H. Hernandez |
D. Rideout |
A. Hamma |
||
| 12:30
-- 13:30 |
J. Kowalski-Glikman | |||||
| 13:30 -- 16:30 |
Lunch
break |
Lunch break | Lunch break | Lunch break | ||
| 16:30 -- 17:30 |
J. Kowalski-Glikman |
|
C. Chryssomalakos |
|||
| 17:30 -- 18:00 |
Travel and Accommodation
General plan
A typical travel arrangement would be as follows:
- Arrival in Athens/Piraeus on Saturday, September
13.
- Morning of Sunday 14 dedicated to sightseeing, etc.
Late lunch, return to the hotel, and on to the port of Piraeus,
by taxi or metro. Departure for the port of Katapola
(Amorgos) at
17:30, arrival in the early
morning of Monday 15 --- a long trip (~9h), crossing a good part of
the Aegean.
- Monday 15 -- Friday 19: GRAVTUM II.
- Saturday 20, 07:20: departure from Aeghiali to Piraeus, arrival at 15:00.
- Sunday 21: flight out of Athens.
Accommodation in Amorgos
The "Conference Hotel" in Tholaria is the family-run
Vigla Hotel
+30 22850 73288
+30 22850 73004
+30 22850 73005
+30 22850 73332 (fax)
vigla.hotel@amorgos.net
http://www.vigla-hotel.amorgos.net
Prices: 38/50 euros per night single (breakfast/halfboard)
60/84 euros per night double (breakfast/halfboard)
Our hosts will be Stefanos and Irene Giannakopoulos, who are extremely helpful and knowledgeable about the island. To make a reservation, please send to the hotel, by e-mail or fax, your name, period of stay, number of persons, bed type, your choice of meal plan, and a credit card number (plus expiration date). Two nights will be charged to the card, nonrefundably, at the moment the reservation is made --- do mention the ``GRAVTUM II Conference'' to get the above rates.
There are several other options for accommodation, both in Tholaria and nearby Aeghiali, including the somewhat upscale hotel Aegialis, halfway between the two villages.
Accommodation in Athens/Piraeus
Accommodation in Piraeus, for the nights before and after the conference, can be at the
Lilia Hotel
131 Zeas Str. Passalimani, Piraeus
+30 210 4179108
+30 210 4179346
+30 210 4119720
+30 210 4114311 (fax)
Reservations: info@liliahotel.gr
http://www.liliahotel.gr
Prices: 58/78 euros per night (single/double, breakfast included)
Getting to Lilia Hotel from the Athens airport is relatively straightforward (see Piraeus map and directions). Other options, especially in the central (but overpriced) Syntagma Square region of Athens can be easily googled --- you get from there to the port by taxi (~6 euros) or a twenty minute ride in the metro. Information on some additional hotels, as well as boat tickets, will be posted in due time (see below in Practicalities section).
It might be of interest to prospective participants that DICE 2008 will take place in Castiglioncello (Tuscany, Italy) the week after GRAVTUM II (Sep 22-26, see DICE 2008 homepage).
Practicalities
Health and safety
While Greece, and Amorgos in particular, are safe places to be, the relative remoteness of the island prevents quick access to full medical care in case of emergency. This might be a factor that pregnant women, parents with babies, and people with particular medical conditions might want to take into account.
Hotel Booking
It is now time to reserve a hotel room in both Amorgos and Athens/Piraeus. If staying at the Lilia Hotel in Piraeus, the prices are now updated as above (please mention the GRAVTUM II conference). Other options, close to Sintagma square, are the Achilleas Hotel and Plaka Hotel.
Boat ticket booking
Boat tickets to Amorgos can be bought online at the site http://www.bluestarferries.com/ENGLISH/defaultmain.htm. The page requires Internet Explorer 4.0 or later. There are three steps in the process that you will most probably figure out as you go along --- if in doubt, consult the brief directions that follow:
STEP 1: Fill out the ``Date'', ``From'', ``To'' fields (=September 14, Piraeus, Katapola), and click on ``Itineraries''. In the popup list choose the appropriate entry, and after the list disappears, fill in the ``Class'' and ``Adults'' etc fields. Ignore the second row of similar fields right below. Repeat with the return trip, from Aighiali to Piraeus. Click on ``Check reservation'' (pressing simultaneously on the Control key of your keyboard if popup windows are blocked on your computer).
STEP 2: Fill in name etc, and check the ``I have read ...'' box. Click on ``Continue''.
STEP 3: Check that all data are correct and fill in the email and phone number fields - feel free to supply my phone number, 6937681205. Click on ``Credit Card Validation''. Fill in the credit card fields and click on ``Send''.
You will receive an eight-digit reservation code, and an access code. If you prefer it, you can send me the reservation code and I can pick up the ticket for you from the agency in Piraeus (Sunday, September 14 departures only!). Otherwise, you can pick up the ticket yourself before departure, from the Blue Star Ferries agency, marked on the Piraeus map linked to above (allow an extra fifteen minutes).