# Is something beyond the material needed to solve the Von Neumann Chain?

A problem has been presented that goes like this:

Particles normally exist as several mathematical possibilities rather than one actual object. It is said that in the absence of observation, particles exist in a superposition of possibilities rather than one actual thing. But when we look they are not in such an indefinite state.

The problem states that the way to solve finding out why there is something definite when we look is decoherence. But it is said that this doesn't really solve the problem because whatever particles were used to collapse another, what was used to collapse that particle? And so on and on.

And the reason for this is because the wave function of a particle cannot be unentangled from that of whatever is used to measure it. When one photon is measured by another they entangle. If one particle measures another, it inherits part of its wave function, and that particle which is supposed to be measuring, cannot be fully explained without what it is measuring.

So you need another measuring device to collapse that initial measuring particle to a definite state. But then you need something else to collapse that measuring apparatus as well, and so on and so on. This creates a chain of material objects in a superposition of measuring, which is known as a Von Neumann chain.

Since quantum laws are what describe all material objects, some other particles or measuring apparatus is always needed to collapse the next one in line. You keep going back until you get to something nonlocal. Outside the entire material system, which escapes this chain by not being bound by the same physical laws, and is able to cause final collapse of everything in the chain, which is argued to be a conscious observer. Something beyond the material with the ability to collapse the entire physical system.

Is this true? If not, why not.

• I think you are having trouble distinguishing between physical facts and explanation models within theories. In the realm of physical facts, there is no collapse of wave functions. In the model of single particle quantum mechanics (which is not even a particularly valid description of reality), the collapse of the wave function is merely a name for the fact that one does not have to understand the details of the quantum mechanics of the measuring apparatus to extract the relevant information from the observed system. Aug 20, 2014 at 3:32