Nobel Week at CMI
Prof. Gerardus 't Hooft (Winner of the 1999 Nobel Prize in
Physics), Professor of Theoretical Physics, Utrecht University,
The Netherlands, will be in residence at the Chennai Mathematical
Institute from November 16 to 22, 2009. During this period, a
number of activities will be held as per the following
schedule. All interested parties are welcome to attend.
Prof. 't Hooft's visit is sponsored by the Academic Alliance between CMI and Tata Consultancy Services.
 DAY 1: Monday, November 16, 2009
Activity: Discussions (35.00 PM) (Tentative)
 DAY 2: Tuesday, November 17, 2009
 Activity 1: Research Seminar
Time: 11.00 am  12.30 pm
Venue: CMI Seminar Hall
Title: Crystalline gravity
Abstract:
Matter interacting classically with gravity in 3+1
dimensions usually gives rise to a continuum of degrees
of freedom, so that, in any attempt to quantize the
theory, ultraviolet divergences are nearly
inevitable. Here, we investigate a theory that only
displays a finite number of degrees of freedom in compact
sections of spacetime. In finite domains, one has only
exact, analytic solutions. This is achieved by limiting
ourselves to straight pieces of string, surrounded by
locally flat sections of spacetime. Next, we suggest
replacing in the string holonomy group, the Lorentz group
by a discrete subgroup, which turns spacetime into a
4dimensional crystal with defects.
 Activity 2: "Teteetete with a Nobel Laureate"
(An Interactive Session with School Students  Strictly
by Invitation)
Time: 4 PM  5.30 PM
Venue: CMI Seminar Hall
 DAY 3: Wednesday, November 18, 2009
 Activity 1: Research Seminar
Time: 11.00 AM  12.30 PM
Venue: CMI Seminar Hall
Title: Deterministic quantum mechanics
Abstract:
Investigating a class of models that is familiar in
studies of cellular automata, we find that quantum
operators can be employed to describe their long distance
behavior. These operators span a Hilbert space that
appears to turn such a model into a genuine quantum field
theory, obeying the usual conditions of locality in terms
of its quantum commutators. Entangled states can be
constructed exactly as in quantum theories. This raises
the question whether such models allow Bell's
inequalities to be violated. Being a local, deterministic
theory, one would argue that this is impossible, but
since at large distance scales the model does not seem to
differ from real quantum field theories, there is reason
to wonder why it should not allow entangled states. The
standard arguments concerning Bell's inequalities are
reexamined in this light.
 Activity 2: Public Lecture
Time: 6.00 PM  7.30 PM
Venue: Triple Helix Auditorium, CLRI
Title: Mini Black Holes and Quantum Physics
Abstract:
The Standard Model of Elementary Particles emerged
empirically as an extremely efficient way to describe all
particles and forces that have been detected experimentally thus
far. However, in these experiments, the gravitational force was
far too weak to be taken into account. In our attempts to include
gravity, we encounter the difficulty that black holes might form.
Their very nature causes unforeseen difficulties when we try to
formulate a theory consistent with quantum mechanics. Is there
information loss? Is quantum mechanics still valid? Will
general relativity be an exact symmetry for very energetic
particles? Something very peculiar seems to happen with clocks
and rulers inside black holes.
 DAY 4: Thursday, November 19, 2009
 Activity: Research Seminar
Time: 3.30 PM
Venue: IMSc
Title: Instantons and scalar mesons
Abstract:
Instantons in QCD are known to break chiral U(N) x U(N)
down to SU(N) x SU(N) x U(1), where N is the number of
flavors. This directly affects the mass spectrum of the
pseudoscalar mesons, since these act as the Goldstone
bosons of this symmetry. It is not so well known,
however, that instantons also have noticeable effects in
the mass spectrum of the scalar mesons. For a long time,
there has been confusion as to whether the excited states
of scalar mesons are biquark or tetraquark
states. Knowing the interactions due to instantons, one
can clarify the situation.
 DAY 5: Friday, November 20, 2009
 Activity: Research Seminar
Time: 11.00 AM  12.30 PM
Venue: CMI Seminar Hall
Title: Quantum gravity without spacetime
singularities or horizons
Abstract:
In an attempt to reestablish spacetime as an essential
frame for formulating quantum gravity  rather than an
"emergent" one  we find that exact invariance
under scale transformations is an essential new
ingredient for such a theory. Use is made of the
principle of "black hole complementarity", the
notion that observers entering a black hole describe its
dynamics in a way that appears to be fundamentally
different from the description by an outside
observer. These differences can be boiled down to
conformal transformations. If we add these to our set of
symmetry transformations, black holes, spacetime
singularities, and horizons disappear.
