Consciousness and collapse

There is nothing bizarre in von Neumann's statement (in his well-known 1932 book on quantum mechanics) that consciousness collapses the wave function.

To say that consciousness collapses the wave function is equivalent to say that it takes consciousness to interpret the universe and change the interpretation when new information arrives.

Instead of modeling the system by a superposition in the absence of information, you model it by one of the participating eigenstates if a measurement result becomes known. Clearly, modeling reality (and changing the model) is a conscious activity and requires consciousness.

This is nothing mysterious, and happens also in classical physics once you have a stochastic dynamics, where the collapse is called conditional probability. See, e.g.,

Moreover, it has nothing to do with superluminal changes, since once one changes a model to describe something, everything in the model changes instantaneously, although the system modelled isn't changed at all. This already happens when you apply a coordinate transformation in a classical system....

Being in a superposition of position states means that there is no exact value of the position, but not that there is no position at all. Systems unobserved by people (e.g. the interior of the Moon) have lots of meaningful properties even in the absence of a sharp position. In particular, the Moon has a mean position and a mean square deviation from this position, which together are adequate position descriptions for most purposes.

Arnold Neumaier (
A theoretical physics FAQ