array9

Would it have mass for instance? lets just assume it is a particle, which cannot interact other than gravity and providing a random state change to other systems.

 It would have to be observable in some way, by at least having a random effect on something else, which was observable.

There would have to be vast quantities of such randomness to support quantum machanical effects, and be distributed in all regions where such effects take place.

Now this does not have to be actually random, but would appear so if we cannot observe anything other than the mass and changes in other systems states.  Indeed it begs the question whether there need be any true randomness anyway, provided the individual particles don't leave any identifiable trail.

Now given this hidden mechanism, it does not need there to be any multi-world interpretation.  It could be purely mechanistic, but also mostly hidden other than its mass.  But internally it would appear totally random and strange

Of course there would be a whole lot of dark matter floating around that nobody could see, other than in large scale observations.  So that is what it is doing.

This is all rather chicken and egg.  

Martin