  Spontaneous collapse models are proposed modifications to quantum mechanics
which aim to solve the measurement problem. In this article we will consider
models which attempt to extend a specific spontaneous collapse model, the
Ghirardi-Rimini-Weber model (GRW), to be consistent with special relativity. We
will present a condition that a relativistic GRW model must meet for three
cases: for single particle, for N distinguishable particles, and for
indistinguishable particles. We will then show that this relativistic condition
implies that one can have a relativistic GRW model for a single particle or for
distinguishable non-interacting, non-entangled particles but not otherwise.
