Dublin Quantum Field Theory Seminar

                            Synge Lecture Theatre
                    School of Mathematics, Hamilton Building
                             Trinity College Dublin

                                 Time: 4.15 pm


November 11  Fay Dowker (Dept. of Physics, QMW, England)

A spontaneous collapse model on a lattice


The spontaneous collapse models of Ghirardi, Rimini and  Weber (GRW),
Pearle and others represent a promising direction of research towards
an observer independent theory of fundamental matter. These models were 
first proposed in a non-relativistic framework and since then much 
attention has focused on the search for appropriately relativistic models.
This is not only important in its own right, but seems to be
a prerequisite to any hope of applying collapse model
ideas to quantum gravity.

I will present a simple collapse model for a field theory,
defined on a $1+1$ null lattice. Being a lattice model, it doesn't enjoy 
exact Lorentz invariance and so it may be argued that it is not 
``relativistic'' at all.  However, it is not unreasonable to hope that 
Lorentz invariance will be attained in an appropriate
continuum limit. Moreover, in the view of some workers, the
aspect of spacetime that is fundamental and survives its
encounter with its quantum nemesis is its causal structure
and, further, that this fundamental causal structure is discrete. 
If one is looking for a development of quantum theory suited to such 
beliefs about quantum gravity, our model has many attractive features: it 
is discrete, there is a causal structure, and there is a local evolution 
rule tied to  that causal structure. I will show that it is very ``local'' 
in construction, though it gives rise to non-local correlations (as 
expected by Bell's Theorem). I will also show that, despite the non-local 
correlations, external agents cannot use the field to send superluminal 
signals. 



Back to seminar list.

Last changed 11 September 2002.