Seminar @ DF-TS - Tue 21 Jul 11:30 am - S. Banerjee - "Solving problems in cosmology and quantum general relativity using collapse models"

[Rosita Glavina - Dip. Fisica UniTS]

We are pleased to announce the seminar @ DF-TheorySection UniTs:
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Shreya Banerjee
Tata Institute of Fundamental Research, Mumbai, India

"Solving problems in cosmology and quantum general relativity using 
collapse models"

Tuesday, 21 Jul 2015 - 11:30 am
Physics Department, LB r. 204, 2nd floor

ABSTRACT:
The success of the inflationary paradigm rests on its ability to explain
the observed classicality of primordial quantum fluctuations despite
their quantum origin. Squeezing of primordial cosmological inhomogeneities
along with the mechanism of decoherence accounts for many aspects
of this quantum to classical transition, although it remains a matter of 
debate
as to whether this is sufficient to explain the issue of realization of 
a single
outcome from a quantum ensemble given that the universe is a closed system.
Apart from decoherence there have been attempts to resolve this issue
through Continuous Spontaneous Localization (CSL), which is a stochastic
nonlinear modification of the non-relativistic Schrodinger equation. In 
this talk,
I shall revisit one such recently proposed working model of 
classicalization
by spontaneous collapse to look for possible modifications to scalar and
tensor power spectra and their implications. I shall show that it can 
potentially
change the consistency relation of single-field models and a precise 
measurement
of tensor spectral tilt and its running could serve as a test of such 
dynamics in the early universe.
Apart from the quantum measurement problem, two of the big puzzles of 
theoretical
physics are the following: (i) There is apparently no time evolution in 
the dynamics
of quantum general relativity, because the allowed quantum states must obey
the Hamiltonian constraint. (ii) The observed value of the cosmological 
constant
is exceedingly small, compared to its natural value, creating a serious 
fine-tuning
problem. In this talk, I shall also discuss a novel proposal to show how 
the three
problems help solve each other.

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The calendar of events taking place at the Physics Department is 
available at https://df.units.it/en/events/all_evnt/