Την Τρίτη 24 Φεβρουαρίου 2025, ώρα 13.00, στην αίθουσα Φ7 του τμήματος Φυσικής,
ο Μάριος Χριστοδούλου,
group leader στο Institute for Quantum Optics and Quantum Information της Βιέννης
θα δώσει ομιλία με τίτλο:
Observables in Table Top Quantum Gravity
Περίληψη: General relativity poses a long-standing puzzle: without a
fixed spacetime to use as reference, it is
notoriously challenging to define physical observables. [1] gave a
first definitive result about
this decades–long question, providing a very sharp formulation of the
‘problem of observables’: in a precise sense of ‘definable’,
provided by a branch of logic called descriptive set theory,
diffeomorphism-invariants are not definable.
These difficulties notwithstanding, the problem of observables can be
fully resolved for background independent theories defined on finite
graphs, as we showed in [2]. Sets of complete observables can be
constructed so that each seeks a connected subgraph structure — local
correlations. Geometrical information is fully encoded in background
independent observables through this subtle interplay of global and
local graph notions, a behavior we term glocal.
In this talk, we discuss the above results as to their relevance
regarding: (i) notions of invariants under quantum coordinates, such
as that appeared in [3] (ii) the epistemological relevance of Table
Top Quantum Gravity protocols
