Mathematical Physics Seminar
December Schedule
Have a safe winter vacation and holiday.
Organizer- Joel L. Lebowitz
email: lebowitz@math.rutgers.edu
- Time/place-11:30am 12/5/2002 in Hill 705
- Speaker- G. Ghirardi, Trieste, Italy
- Title- A general argument against the universal
validity of the superposition principle
- Abstract- We reconsider the problems that standard quantum theory
meets with the macro-objectification process and we rederive the general
conclusion that serious problems of interpretation arise. The novelty of
the approach derives from the fact that the conclusion is obtained under
extremely general conditions, in particular without resorting to any of the
assumptions of ideality of the measurement process. In particular we take
into account possible malfunctionings of the apparatus, its unavoidable
entanglement with the environment, its high but not perfect reliability and
the fact that we have only a quite limited control of most of its degrees
of freedom. The conclusion is that the very possibility of getting
information about a microsystem through measurement processes, combined
with the general validity of the linear nature of the evolution leads to a
basic contradiction.
- Time/place- 12/12/2002
NO SEMINAR
- Time/place-11:30am 12/13/2002 in Hill 705
- Speaker- E. Caglioti, University of Rome, Italy
- Title- Stability vs. Instability of the Scaling Dynamics
of a Massive Piston in an Ideal Gas
- Abstract-The dynamics of a massive piston of mass M=N^2/3
in a gas of N non-interacting
point particles
has been extensively studied. A very interesting problem is to decribe the time
evolution of the system
when the initial conditions are chosen far from equilibrium.
In particular, while there is numerically evidence that the system reaches
asymptotically the equilibrium,
a strange behavior of the system has been found for intermediate times.
For example, for some initial conditions, the piston develops long standing
macroscopic
oscillations.
Here an analysis of the solutions of a suitable hydrodynamical equation (HE),
that has been proved to decribe the
system for short times, is performed.
In particular we study linear and nonlinear stability of the stationary
solutions of the HE, and we present an approximate construction of
periodic solutions of the HE.
The results of this analysis give informations on the time evolution of the
particle system for intermediate times. In particular there is
numerical evidence that the piston does not develop macroscopic oscillation
only when the initial condition is a stationary stable solution of the HE,
while the long standing oscillation of the
piston seems to be well described by the periodic solution of the HE found.
This work has been done in collaboration with N. Chernov and J. Lebowitz.
- Time/place- 12/19/2002
NO SEMINAR
- Time/place- 12/26/2002
NO SEMINAR