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marcus

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## Main Question or Discussion Point

Next week will be the 13th conference in the

It will be held at Salonica (Thessaloniki, Greece)

Here are titles of some of the talks

Ashtekar--

Loll---

Pullin--

Randono--

All four talks will be on 5 June, the first three in the main session (presumably they are invited talks) and the fourth will be in the parallel session a bit later. So there is no time conflict.

http://www.astro.auth.gr/~neb-13/

They are going to talking about things that currently interest a lot of people. LQC has been making remarkable progress especially since 2005 in Ashtekar's group at Penn State. Getting rid of the big bang singularity---running computer and analytical model through and back before the big bang. So it was natural to invite Ashtekar to give an overview.

Loll's Utrecht group has also been getting results rapidly. One of the recent ones was the emergence of a deSitter universe, as a spacetime path integral: the smooth quantum "average" of many jagged geometries. The thing assembled itself out of microscopic degrees of freedom. Getting a 4D spacetime, not put in by hand, to emerge has been a major goal. So that was a clear choice as well.

There has also been much interest in loop quantum black holes, that Jorge Pullin will be talking about.

What is unexpected here is that Andy Randono is giving his paper on mesoscopic QG features that could be pointing to observable effects. Potentially observable effects of QG is another hot topic. Randono is postdoc at Penn State. His going to Salonica with this highlights the possibility of his research (posted only last week) eventually leading to tests. Somebody evidently thinks there is enough to it to warrent a travel grant. I'll give the abstract in case anyone wants to see it.

http://arxiv.org/abs/0805.2955

Andrew Randono

10 pages, 2 figures

(Submitted on 19 May 2008)

"We explore the symmetry reduced form of a non-perturbative solution to the constraints of quantum gravity corresponding to quantum de Sitter space. The system has a remarkably precise analogy with the non-relativistic formulation of a particle falling in a constant gravitational field that we exploit in our anaylsis. We find that the solution reduces to de Sitter space in the semi-classical limit, but the uniquely quantum features of the solution have peculiar property. Namely, the unambiguous quantum structures are neither of Planck scale nor of cosmological scale. Instead, we find a periodicity in the volume of the universe whose period, using the observed value of the cosmological constant, is on the order of the volume of the proton."

**Recent Developments in Gravity**series.It will be held at Salonica (Thessaloniki, Greece)

Here are titles of some of the talks

Ashtekar--

**Loop Quantum Cosmology: an Overview**Loll---

**The Self-Organizing deSitter Universe**Pullin--

**Black Holes in Loop Quantum Cosmology**Randono--

**Mesoscopic Structures in Quantum Gravity**All four talks will be on 5 June, the first three in the main session (presumably they are invited talks) and the fourth will be in the parallel session a bit later. So there is no time conflict.

http://www.astro.auth.gr/~neb-13/

They are going to talking about things that currently interest a lot of people. LQC has been making remarkable progress especially since 2005 in Ashtekar's group at Penn State. Getting rid of the big bang singularity---running computer and analytical model through and back before the big bang. So it was natural to invite Ashtekar to give an overview.

Loll's Utrecht group has also been getting results rapidly. One of the recent ones was the emergence of a deSitter universe, as a spacetime path integral: the smooth quantum "average" of many jagged geometries. The thing assembled itself out of microscopic degrees of freedom. Getting a 4D spacetime, not put in by hand, to emerge has been a major goal. So that was a clear choice as well.

There has also been much interest in loop quantum black holes, that Jorge Pullin will be talking about.

What is unexpected here is that Andy Randono is giving his paper on mesoscopic QG features that could be pointing to observable effects. Potentially observable effects of QG is another hot topic. Randono is postdoc at Penn State. His going to Salonica with this highlights the possibility of his research (posted only last week) eventually leading to tests. Somebody evidently thinks there is enough to it to warrent a travel grant. I'll give the abstract in case anyone wants to see it.

http://arxiv.org/abs/0805.2955

**A Mesoscopic Quantum Gravity Effect**Andrew Randono

10 pages, 2 figures

(Submitted on 19 May 2008)

"We explore the symmetry reduced form of a non-perturbative solution to the constraints of quantum gravity corresponding to quantum de Sitter space. The system has a remarkably precise analogy with the non-relativistic formulation of a particle falling in a constant gravitational field that we exploit in our anaylsis. We find that the solution reduces to de Sitter space in the semi-classical limit, but the uniquely quantum features of the solution have peculiar property. Namely, the unambiguous quantum structures are neither of Planck scale nor of cosmological scale. Instead, we find a periodicity in the volume of the universe whose period, using the observed value of the cosmological constant, is on the order of the volume of the proton."

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