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Is there a relativistic measurement theory?
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Real measurements take time, and are not instantaneous.
To treat the collapse as instantaneous is an idealization,
valid for many applications of quantum mechanics.

If relativistic effects play a role, one needs to use 
quantum field theory. However, the measurement process in 
quantum field theory is very poorly researched.
Thus statements about the conflict of instantaneous collapse 
and relativity theory are based on very shaky grounds.

For measurement in the relativistic case (but without
invoking field theory) in the most down to earth interpretation 
(i.e., the main stream view), see:

A. Peres,
Classical interventions in quantum systems. 
I. The measuring process
Phys. Rev. A 61, 022116 (2000).
http://arxiv.org/pdf/quant-ph/9906023
II. Relativistic invariance
Phys. Rev. A 61, 022117 (2000)
http://arxiv.org/pdf/quant-ph/9906034

A. Peres,
Quantum information and relativity theory
Rev. Mod. Phys. 76, 93–123 (2004)
http://arxiv.org/pdf/quant-ph/0212023

After having read that, you'll probably be immune against many 
potential infections in this area.

These papers indicate the absence of problems, as far as such a 
simplified analysis can be trusted.



A relativistic dynamic collapse model is given in
http://lanl.arxiv.org/abs/1003.2774