Speaker
Dr
Mohammad Bahrami
(research fellow)
Description
Unification of gravity and quantum theory is still an unattained problem
of modern physics. The traditional approach of quantizing the gravitational
field
has not yet provided us with a satisfying theory of quantum gravity. A different
resolution is to modify quantum dynamics by adding nonlinear terms with
gravitational origins. This line of research is highly motivated by
semi-classical models of gravity, which bring about Schrodinger-Newton (SN)
equation: a deterministic nonlinear Schrodinger equation with Newtonian
self-gravity as nonlinearity. We will quantify the regime where SN equation
can be distinguished from Schrodinger equation. We also argue that SN
equation does not describe the collapse of the wave function, thus one still
needs the collapse postulate. Then, we explicitly show that SN equation
gives rise to superluminal effects, as expected from any deterministic
nonlinear Schrodinger equation. We finally discuss that combining Newtonian
nonlinearity with stochastic terms to avoid superluminality and to describe
the collapse, as in Diosi-Penrose model, is still problematic.
